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Home / DTC / P0038 — HO2S Heater Control Circuit High Bank 1 Sensor 2

P0038 — HO2S Heater Control Circuit High Bank 1 Sensor 2

Detailed page for trouble code P0038.

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Code

P0038

Generic P — Powertrain

HO2S Heater Control Circuit High Bank 1 Sensor 2

Brand: Generic
Type: P — Powertrain
Views: UK: 24 EN: 55 RU: 32
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or high-resistance heater circuit (broken wire, corroded connector)
  • Short to battery voltage on heater control/return circuit
  • Blown fuse or fusible link supplying the heater
  • Failed oxygen sensor (heater element open or internally shorted)
  • Poor or corroded connector/pins at the sensor or harness
  • PCM/ECM heater driver fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Possible failed emissions test or stored emissions-related readiness code
  • Check-engine light may stay on after startup
  • Usually no major drivability issues, but fuel trims or catalyst monitoring may be affected
  • Reduced heater operation can increase catalyst light-off time and emissions

What to check

  • Read freeze frame and freeze-frame data, confirm P0038 is current/confirmed
  • Visually inspect sensor wiring, connector, and harness for damage, corrosion or disconnection
  • Check related fuses and relays for the O2 sensor heater circuit
  • Backprobe heater power and control wires at the sensor connector while performing heater command
  • Measure heater element resistance at the sensor (unplugged)
  • Check for voltage short to battery and for continuity to PCM ground on the control circuit

Signal parameters

  • Heater element resistance (sensor unplugged): typically low (commonly ~2–50 ohms depending on sensor) — should not be open (>infinite)
  • Supply side (battery/fused): battery voltage present (approx. 11–14 V) with key ON
  • Control/driver side when PCM commands heater ON: expected near ground (low voltage, typically
  • If circuit is 'high' the measured voltage on the control circuit may be higher than the PCM expects (indicating open or short to voltage)

Diagnostic algorithm

  1. Verify the code with a scan tool. Note freeze frame data and readiness status. Clear code and attempt to re-run to confirm.
  2. Perform a visual inspection of the Bank 1 Sensor 2 connector, wiring, and nearby harness for heat damage, corrosion, or chafing.
  3. Check fuses/relays related to O2 sensor heaters. Replace any blown fuse and retest.
  4. With ignition OFF, disconnect the sensor. Measure heater element resistance across the heater pins. If open/infinite, replace the sensor.
  5. With backprobe and key ON, verify battery voltage at the heater supply pin. If no supply, trace supply circuit to fuse/relay/battery.
  6. Command the heater ON with a bi-directional scan tool (if available). Measure voltage on the control/driver pin. If PCM grounds the circuit, the driver pin should go low when commanded ON. If it remains high, check for short to battery or open in the ground path.
  7. Check continuity from the sensor control pin to the PCM; check for shorts to battery on that wire. Repair any wiring faults or connectors found.
  8. If wiring and sensor test good, test or replace the PCM only after confirming driver fault with proper test equipment or manufacturer procedures.
  9. After repairs, clear codes and perform a drive cycle to verify code does not return and that readiness tests complete.

Likely causes

  • Disconnected or damaged sensor connector at Bank 1 Sensor 2
  • Open heater element inside the downstream O2 sensor
  • Wiring shorted to battery voltage (power side) or open on control/ground side
  • Blown heater fuse for oxygen sensors
  • Corroded ground or wiring harness chafed at heat/sharp edge

Fault status

⚠️ Status
HO2S Heater Control Circuit High - Bank 1 Sensor 2
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.8-2.5 hours

Similar codes

P0037 P0058 P0135 P0138 P0141
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Code

P0038

HUMMER P — Powertrain

Heated Oxygen Sensor (HO2S) Heater Circuit High Voltage Bank 1 Sensor 2

Brand: HUMMER
Type: P — Powertrain
Views: UK: 10 EN: 41 RU: 11
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or high-resistance heater circuit (broken wire, corroded connector)
  • Short to battery voltage on heater control/return circuit
  • Blown fuse or fusible link supplying the heater
  • Failed oxygen sensor (heater element open or internally shorted)
  • Poor or corroded connector/pins at the sensor or harness
  • PCM/ECM heater driver fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Possible failed emissions test or stored emissions-related readiness code
  • Check-engine light may stay on after startup
  • Usually no major drivability issues, but fuel trims or catalyst monitoring may be affected
  • Reduced heater operation can increase catalyst light-off time and emissions

What to check

  • Read freeze frame and freeze-frame data, confirm P0038 is current/confirmed
  • Visually inspect sensor wiring, connector, and harness for damage, corrosion or disconnection
  • Check related fuses and relays for the O2 sensor heater circuit
  • Backprobe heater power and control wires at the sensor connector while performing heater command
  • Measure heater element resistance at the sensor (unplugged)
  • Check for voltage short to battery and for continuity to PCM ground on the control circuit

Signal parameters

  • Heater element resistance (sensor unplugged): typically low (commonly ~2–50 ohms depending on sensor) — should not be open (>infinite)
  • Supply side (battery/fused): battery voltage present (approx. 11–14 V) with key ON
  • Control/driver side when PCM commands heater ON: expected near ground (low voltage, typically
  • If circuit is 'high' the measured voltage on the control circuit may be higher than the PCM expects (indicating open or short to voltage)

Diagnostic algorithm

  1. Verify the code with a scan tool. Note freeze frame data and readiness status. Clear code and attempt to re-run to confirm.
  2. Perform a visual inspection of the Bank 1 Sensor 2 connector, wiring, and nearby harness for heat damage, corrosion, or chafing.
  3. Check fuses/relays related to O2 sensor heaters. Replace any blown fuse and retest.
  4. With ignition OFF, disconnect the sensor. Measure heater element resistance across the heater pins. If open/infinite, replace the sensor.
  5. With backprobe and key ON, verify battery voltage at the heater supply pin. If no supply, trace supply circuit to fuse/relay/battery.
  6. Command the heater ON with a bi-directional scan tool (if available). Measure voltage on the control/driver pin. If PCM grounds the circuit, the driver pin should go low when commanded ON. If it remains high, check for short to battery or open in the ground path.
  7. Check continuity from the sensor control pin to the PCM; check for shorts to battery on that wire. Repair any wiring faults or connectors found.
  8. If wiring and sensor test good, test or replace the PCM only after confirming driver fault with proper test equipment or manufacturer procedures.
  9. After repairs, clear codes and perform a drive cycle to verify code does not return and that readiness tests complete.

Likely causes

  • Disconnected or damaged sensor connector at Bank 1 Sensor 2
  • Open heater element inside the downstream O2 sensor
  • Wiring shorted to battery voltage (power side) or open on control/ground side
  • Blown heater fuse for oxygen sensors
  • Corroded ground or wiring harness chafed at heat/sharp edge

Fault status

⚠️ Status
HO2S Heater Control Circuit High - Bank 1 Sensor 2
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.8-2.5 hours

Similar codes

P0037 P0058 P0135 P0138 P0141
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Code

P0038

LAND ROVER P — Powertrain

High Heated Oxygen Sensor Heater Control Circuit (bank 1 sensor 2)

Brand: LAND ROVER
Type: P — Powertrain
Views: UK: 6 EN: 30 RU: 9
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or high-resistance heater circuit (broken wire, corroded connector)
  • Short to battery voltage on heater control/return circuit
  • Blown fuse or fusible link supplying the heater
  • Failed oxygen sensor (heater element open or internally shorted)
  • Poor or corroded connector/pins at the sensor or harness
  • PCM/ECM heater driver fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Possible failed emissions test or stored emissions-related readiness code
  • Check-engine light may stay on after startup
  • Usually no major drivability issues, but fuel trims or catalyst monitoring may be affected
  • Reduced heater operation can increase catalyst light-off time and emissions

What to check

  • Read freeze frame and freeze-frame data, confirm P0038 is current/confirmed
  • Visually inspect sensor wiring, connector, and harness for damage, corrosion or disconnection
  • Check related fuses and relays for the O2 sensor heater circuit
  • Backprobe heater power and control wires at the sensor connector while performing heater command
  • Measure heater element resistance at the sensor (unplugged)
  • Check for voltage short to battery and for continuity to PCM ground on the control circuit

Signal parameters

  • Heater element resistance (sensor unplugged): typically low (commonly ~2–50 ohms depending on sensor) — should not be open (>infinite)
  • Supply side (battery/fused): battery voltage present (approx. 11–14 V) with key ON
  • Control/driver side when PCM commands heater ON: expected near ground (low voltage, typically
  • If circuit is 'high' the measured voltage on the control circuit may be higher than the PCM expects (indicating open or short to voltage)

Diagnostic algorithm

  1. Verify the code with a scan tool. Note freeze frame data and readiness status. Clear code and attempt to re-run to confirm.
  2. Perform a visual inspection of the Bank 1 Sensor 2 connector, wiring, and nearby harness for heat damage, corrosion, or chafing.
  3. Check fuses/relays related to O2 sensor heaters. Replace any blown fuse and retest.
  4. With ignition OFF, disconnect the sensor. Measure heater element resistance across the heater pins. If open/infinite, replace the sensor.
  5. With backprobe and key ON, verify battery voltage at the heater supply pin. If no supply, trace supply circuit to fuse/relay/battery.
  6. Command the heater ON with a bi-directional scan tool (if available). Measure voltage on the control/driver pin. If PCM grounds the circuit, the driver pin should go low when commanded ON. If it remains high, check for short to battery or open in the ground path.
  7. Check continuity from the sensor control pin to the PCM; check for shorts to battery on that wire. Repair any wiring faults or connectors found.
  8. If wiring and sensor test good, test or replace the PCM only after confirming driver fault with proper test equipment or manufacturer procedures.
  9. After repairs, clear codes and perform a drive cycle to verify code does not return and that readiness tests complete.

Likely causes

  • Disconnected or damaged sensor connector at Bank 1 Sensor 2
  • Open heater element inside the downstream O2 sensor
  • Wiring shorted to battery voltage (power side) or open on control/ground side
  • Blown heater fuse for oxygen sensors
  • Corroded ground or wiring harness chafed at heat/sharp edge

Fault status

⚠️ Status
HO2S Heater Control Circuit High - Bank 1 Sensor 2
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.8-2.5 hours

Similar codes

P0037 P0058 P0135 P0138 P0141
Workshop Manuals

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Workshop Manual
Defender 300Tdi Years: 1996 Manual in English 7.5 MB
Short description

Official workshop manual for the Land Rover Defender 300Tdi (from 1996 model year). Contains specifications, adjustment, fault diagnosis and step-by-step repair and overhaul procedures for engine, transmission, axles, suspension, brakes, electrical and body. Intended for dealer workshops and trained technicians.

199,00 UAH
Contents
Key sections:
  • 01 INTRODUCTION
  • 04 GENERAL SPECIFICATION DATA
  • 05 ENGINE TUNING DATA
  • 07 GENERAL FITTING REMINDERS
  • 09 LUBRICANTS, FLUIDS AND CAPACITIES
  • 10 MAINTENANCE
  • 12 ENGINE Tdi
  • - Description and operation
  • - Fault diagnosis
  • - Adjustment
  • - Repair and overhaul procedures
  • 19 FUEL SYSTEM Tdi
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Short description

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199,00 UAH
Contents
Key sections:
  • 01 - INTRODUCTION
  • - Introduction
  • - Dimensions
  • - References
  • - Repairs and replacements
  • - Poisonous substances
  • - Fuel handling precautions
  • - Synthetic rubber
  • - Recommended sealants
  • - Used engine oil precautions
  • - Accessories and conversions
  • - Wheels and tyres
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Short description

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199,00 UAH
Contents
Key sections:
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  • 1.1 About this document
  • 1.2 Battery voltage
  • 1.3 Electrical precautions
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  • 1.6 Abbreviations
  • 1.7 HeVAC, sensors abbreviations
  • 1.8 How to use this document
  • 1.9 Connector detail format
  • 1.10 Fault diagnosis
  • 1.11 Wire colour codes
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Code

P0038

MITSUBISHI P — Powertrain

Oxygen sensor heater(rear) high

Brand: MITSUBISHI
Type: P — Powertrain
Views: UK: 10 EN: 41 RU: 11
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Page language: EN

Causes

  • Open or high-resistance heater circuit (broken wire, corroded connector)
  • Short to battery voltage on heater control/return circuit
  • Blown fuse or fusible link supplying the heater
  • Failed oxygen sensor (heater element open or internally shorted)
  • Poor or corroded connector/pins at the sensor or harness
  • PCM/ECM heater driver fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Possible failed emissions test or stored emissions-related readiness code
  • Check-engine light may stay on after startup
  • Usually no major drivability issues, but fuel trims or catalyst monitoring may be affected
  • Reduced heater operation can increase catalyst light-off time and emissions

What to check

  • Read freeze frame and freeze-frame data, confirm P0038 is current/confirmed
  • Visually inspect sensor wiring, connector, and harness for damage, corrosion or disconnection
  • Check related fuses and relays for the O2 sensor heater circuit
  • Backprobe heater power and control wires at the sensor connector while performing heater command
  • Measure heater element resistance at the sensor (unplugged)
  • Check for voltage short to battery and for continuity to PCM ground on the control circuit

Signal parameters

  • Heater element resistance (sensor unplugged): typically low (commonly ~2–50 ohms depending on sensor) — should not be open (>infinite)
  • Supply side (battery/fused): battery voltage present (approx. 11–14 V) with key ON
  • Control/driver side when PCM commands heater ON: expected near ground (low voltage, typically
  • If circuit is 'high' the measured voltage on the control circuit may be higher than the PCM expects (indicating open or short to voltage)

Diagnostic algorithm

  1. Verify the code with a scan tool. Note freeze frame data and readiness status. Clear code and attempt to re-run to confirm.
  2. Perform a visual inspection of the Bank 1 Sensor 2 connector, wiring, and nearby harness for heat damage, corrosion, or chafing.
  3. Check fuses/relays related to O2 sensor heaters. Replace any blown fuse and retest.
  4. With ignition OFF, disconnect the sensor. Measure heater element resistance across the heater pins. If open/infinite, replace the sensor.
  5. With backprobe and key ON, verify battery voltage at the heater supply pin. If no supply, trace supply circuit to fuse/relay/battery.
  6. Command the heater ON with a bi-directional scan tool (if available). Measure voltage on the control/driver pin. If PCM grounds the circuit, the driver pin should go low when commanded ON. If it remains high, check for short to battery or open in the ground path.
  7. Check continuity from the sensor control pin to the PCM; check for shorts to battery on that wire. Repair any wiring faults or connectors found.
  8. If wiring and sensor test good, test or replace the PCM only after confirming driver fault with proper test equipment or manufacturer procedures.
  9. After repairs, clear codes and perform a drive cycle to verify code does not return and that readiness tests complete.

Likely causes

  • Disconnected or damaged sensor connector at Bank 1 Sensor 2
  • Open heater element inside the downstream O2 sensor
  • Wiring shorted to battery voltage (power side) or open on control/ground side
  • Blown heater fuse for oxygen sensors
  • Corroded ground or wiring harness chafed at heat/sharp edge

Fault status

⚠️ Status
HO2S Heater Control Circuit High - Bank 1 Sensor 2
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.8-2.5 hours

Similar codes

P0037 P0058 P0135 P0138 P0141
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