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Home / DTC / P1157 — O2 Sensor Heater Circuit High Voltage Bank 2 Sensor 2

P1157 — O2 Sensor Heater Circuit High Voltage Bank 2 Sensor 2

Detailed page for trouble code P1157.

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Code

P1157

BMW P — Powertrain

O2 Sensor Heater Circuit High Voltage Bank 2 Sensor 2

Brand: BMW
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
Repair manuals

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Code

P1157

BUICK P — Powertrain

HO2S Bank 2 Sensor 2 Lean System Or Low Voltage

Brand: BUICK
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
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Code

P1157

CADILLAC P — Powertrain

HO2S Bank 2 Sensor 2 Lean System Or Low Voltage

Brand: CADILLAC
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
206

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Code

P1157

CHEVROLET P — Powertrain

HO2S Bank 2 Sensor 2 Lean System Or Low Voltage

Brand: CHEVROLET
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
456

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CHEVROLET

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Code

P1157

CHRYSLER P — Powertrain

HO2S Bank 2 Sensor 2 Lean System Or Low Voltage

Brand: CHRYSLER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
173

Browse 173 CHRYSLER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

CHRYSLER

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
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Code

P1157

CITROEN P — Powertrain

Electric throttle signal malfunction

Brand: CITROEN
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
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+100 karma for a short comment :)
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Code

P1157

DS P — Powertrain

Electric throttle signal malfunction

Brand: DS
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
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+100 karma for a short comment :)
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Send to email
Code

P1157

FORD P — Powertrain

Lack of Downstream Heated Oxygen Sensor Switch Sensor Indicates Lean Bank 2

Brand: FORD
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
Your experience will help others
+100 karma for a short comment :)
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Code

P1157

GM P — Powertrain

HO2S Bank 2 Sensor 2 Lean System Or Low Voltage

Brand: GM
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
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Code

P1157

GMC P — Powertrain

HO2S Bank 2 Sensor 2 Lean System Or Low Voltage

Brand: GMC
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
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Code

P1157

HUMMER P — Powertrain

Heated Oxygen Sensor (HO2S) Bank 2 Sensor 2 Lean System or Low Voltage

Brand: HUMMER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
Repair manuals

Manual library for HUMMER

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Code

P1157

JAGUAR P — Powertrain

Lack Of HO2S22 Switches Sensor Indicates Lean

Brand: JAGUAR
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
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Code

P1157

LAND ROVER P — Powertrain

Missing key H02S-22, sensor indicates tilt

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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Code

P1157

LINCOLN P — Powertrain

Lack of Downstream Heated Oxygen Sensor Switch Sensor Indicates Lean Bank 2

Brand: LINCOLN
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
166

Browse 166 LINCOLN manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LINCOLN

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Code

P1157

MERCURY P — Powertrain

Lack of Downstream Heated Oxygen Sensor Switch Sensor Indicates Lean Bank 2

Brand: MERCURY
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
296

Browse 296 MERCURY manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MERCURY

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Code

P1157

OLDSMOBILE P — Powertrain

HO2S Bank 2 Sensor 2 Lean System Or Low Voltage

Brand: OLDSMOBILE
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
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Send to email
Code

P1157

Other P — Powertrain

Lack Of HO2S22 Switch - Sensor Indicates Lean

Brand: Other
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
9,086

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Code

P1157

PEUGEOT P — Powertrain

Electric throttle signal malfunction

Brand: PEUGEOT
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
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Code

P1157

SATURN P — Powertrain

HO2S Bank 2 Sensor 2 Lean System Or Low Voltage

Brand: SATURN
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
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Code

P1157

VOLKSWAGEN P — Powertrain

Manifold Absolute Pressure Sensor Circuit Power Supply Malfunction

Brand: VOLKSWAGEN
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to battery voltage on the O2 heater supply or control wire
  • Failed O2 sensor with internal heater fault
  • Corroded or damaged sensor connector or wiring harness
  • Blown fuse or faulty relay for heater circuit
  • Poor or missing ground on heater control circuit
  • ECM or driver transistor fault

Symptoms

  • Malfunction Indicator Lamp (MIL/CEL) illuminated
  • Possible failed emissions test (catalyst/monitor incomplete)
  • Diagnostic trouble codes stored for O2 heater
  • No major drivability loss in most cases (heater affects readiness/emissions)

What to check

  • Read DTCs and freeze-frame/live data to confirm P1157 and related codes
  • Verify vehicle-specific Bank 2 / Sensor 2 location and connector pinout
  • Visual inspection of sensor connector and wiring for heat, chafing, corrosion, or damage
  • Check fuse(s) and relay(s) related to O2 sensor heaters
  • Backprobe heater supply and control wires with key ON to verify voltage
  • Measure heater element resistance at the sensor connector with sensor disconnected

Signal parameters

  • Expected heater resistance: typically low (example 2–20 Ω) — check OEM spec for exact value
  • Heater supply voltage: near battery voltage (~11–14 V) when power present
  • Heater control: ECM usually switches ground or PWM; control line may be low-side switched
  • Fault condition: measured voltage or feedback indicates higher than expected level on heater circuit

Diagnostic algorithm

  1. Connect a professional scan tool. Read and record P1157 plus any other codes and freeze-frame data.
  2. Confirm Bank 2 Sensor 2 identity on the vehicle (downstream side of catalytic converter).
  3. Perform a visual inspection of the sensor, connector, and wiring from sensor to ECM for damage or corrosion.
  4. Check relevant fuses and relays for the O2 heater circuit; replace if faulty.
  5. With ignition ON (engine OFF), backprobe the heater supply pin at the sensor connector and verify battery voltage is present only where expected.
  6. Measure heater element resistance at the sensor (sensor disconnected). Compare to OEM spec; if open or shorted, replace the sensor.
  7. Command the heater ON with a scan tool (if supported) and observe supply/control voltage and current. Look for short to power or stuck-high signals.
  8. If supply shows constant high voltage where a switched signal is expected, trace wiring for a short to battery or damaged insulation. Repair wiring or connector as needed.
  9. If wiring and sensor check good but code persists, verify continuity and resistance from sensor connector to ECM connector and test ECM driver output. Replace ECM only after confirming wiring and sensor faults are not present.
  10. Clear codes, perform drive cycle and re-check for reoccurrence and monitor heater operation and readiness monitors.

Likely causes

  • Wiring short to constant 12V on heater circuit
  • Open/short in connector (corrosion, bent pin) at sensor
  • Failed heater element inside the sensor
  • Blown/weak fuse or intermittent relay for O2 heater
  • Faulty ECM heater driver (less common)

Fault status

⚠️ Status
O2 sensor heater circuit voltage detected above expected threshold for Bank 2 Sensor 2. ECM logged P1157 and may illuminate MIL. Inspect heater wiring, connector, fuse/relay and sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0158 P0138 P0141 P0135 P0157
626

Browse 626 VOLKSWAGEN manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

VOLKSWAGEN

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