Code
P1197
DODGE
P — Powertrain
O2 Sensor 1/2 Bank 1 Sensor 2 Slow During Catalyst Monitor
Views:
UK: 17
EN: 31
RU: 28
AI status
Completed
Completed
100%
Causes
- Aging or contaminated downstream O2 sensor (Bank 1 Sensor 2)
- Heater circuit open/weak or slow to reach operating temperature
- Damaged wiring, corroded connector pins, or poor ground to the sensor
- Exhaust leaks upstream of the sensor altering signal behavior
- Plugged or failing catalytic converter changing post‑cat response
- Engine running issues (fuel trim extremes, misfire) affecting exhaust composition
Symptoms
- Check Engine Light (MIL) illuminated and readiness monitor failed for catalyst
- Failed catalyst/catalyst monitor on vehicle inspection
- Poor fuel economy or increased emissions (may be subtle)
- Possible rough idle or drivability complaints if sensor/heater or engine condition is affecting closed‑loop control
What to check
- Read DTCs and freeze‑frame data with a full‑function scan tool
- Verify readiness and catalyst monitor status
- Inspect sensor connector and wiring for corrosion, damage, or loose pins
- Monitor live O2 sensor voltages for Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) while engine warms and during induced rich/lean events
- Confirm downstream sensor response time versus upstream sensor: downstream should be less switching but should show change after fuel/AFR step
- Check heater supply voltage and ground at connector with ignition on; measure heater resistance with sensor disconnected
Signal parameters
- Upstream narrowband O2 (Bank 1 Sensor 1): rapid switching approximately 0.1–0.9 V when in closed loop
- Downstream O2 (Bank 1 Sensor 2): should be relatively steady compared to upstream but must still show response to deliberate rich/lean changes (small voltage shift)
- Expected downstream response: a measurable change in voltage within a few seconds after induced exhaust composition change
- Heater circuit: supply voltage near battery voltage with ignition on; heater resistance typically low (varies by sensor, commonly single‑digit to low tens of ohms)
Diagnostic algorithm
- Confirm P1197 present and note freeze frame and related codes. Clear code and attempt a drive cycle to reproduce.
- Visual inspection: check Bank 1 Sensor 2 connector for corrosion, water intrusion, broken wires, or poor grounds. Repair any damage.
- With scan tool, observe Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) voltages during warm idle and during commanded rich/lean events (throttle blips or induced fuel trim changes). Downstream should change within seconds.
- Test heater circuit: with ignition off disconnect sensor and measure heater resistance; compare to spec or typical range. With ignition on, verify reference voltage/power to heater and good ground.
- Check for exhaust leaks between catalyst and downstream sensor; repair as needed and retest.
- If wiring and heater are good but the downstream sensor shows minimal/very slow change, replace the downstream O2 sensor (Bank 1 Sensor 2). After replacement, clear codes and perform drive cycle to confirm monitor completion.
- If new sensor does not restore normal behavior, evaluate catalytic converter efficiency and PCM operation; perform catalyst temperature/pressure tests or consult manufacturer service data.
- Note: follow OEM safety and immobilizer procedures; avoid open exhaust while hot and use vehicle‑specific test values when available.
Likely causes
- Contaminated or worn downstream O2 sensor
- Faulty heater element or heater circuit for Bank 1 Sensor 2
- Corroded/damaged sensor connector or broken wiring
- Exhaust leak between catalyst and sensor affecting readings
Fault status
Status
Downstream O2 sensor (Bank 1 Sensor 2) response is slower than expected during catalyst monitor — monitor failed.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
P1197
FORD
P — Powertrain
Key Off Voltage Low
Views:
UK: 17
EN: 21
RU: 23
AI status
Completed
Completed
100%
Causes
- Aging or contaminated downstream O2 sensor (Bank 1 Sensor 2)
- Heater circuit open/weak or slow to reach operating temperature
- Damaged wiring, corroded connector pins, or poor ground to the sensor
- Exhaust leaks upstream of the sensor altering signal behavior
- Plugged or failing catalytic converter changing post‑cat response
- Engine running issues (fuel trim extremes, misfire) affecting exhaust composition
Symptoms
- Check Engine Light (MIL) illuminated and readiness monitor failed for catalyst
- Failed catalyst/catalyst monitor on vehicle inspection
- Poor fuel economy or increased emissions (may be subtle)
- Possible rough idle or drivability complaints if sensor/heater or engine condition is affecting closed‑loop control
What to check
- Read DTCs and freeze‑frame data with a full‑function scan tool
- Verify readiness and catalyst monitor status
- Inspect sensor connector and wiring for corrosion, damage, or loose pins
- Monitor live O2 sensor voltages for Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) while engine warms and during induced rich/lean events
- Confirm downstream sensor response time versus upstream sensor: downstream should be less switching but should show change after fuel/AFR step
- Check heater supply voltage and ground at connector with ignition on; measure heater resistance with sensor disconnected
Signal parameters
- Upstream narrowband O2 (Bank 1 Sensor 1): rapid switching approximately 0.1–0.9 V when in closed loop
- Downstream O2 (Bank 1 Sensor 2): should be relatively steady compared to upstream but must still show response to deliberate rich/lean changes (small voltage shift)
- Expected downstream response: a measurable change in voltage within a few seconds after induced exhaust composition change
- Heater circuit: supply voltage near battery voltage with ignition on; heater resistance typically low (varies by sensor, commonly single‑digit to low tens of ohms)
Diagnostic algorithm
- Confirm P1197 present and note freeze frame and related codes. Clear code and attempt a drive cycle to reproduce.
- Visual inspection: check Bank 1 Sensor 2 connector for corrosion, water intrusion, broken wires, or poor grounds. Repair any damage.
- With scan tool, observe Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) voltages during warm idle and during commanded rich/lean events (throttle blips or induced fuel trim changes). Downstream should change within seconds.
- Test heater circuit: with ignition off disconnect sensor and measure heater resistance; compare to spec or typical range. With ignition on, verify reference voltage/power to heater and good ground.
- Check for exhaust leaks between catalyst and downstream sensor; repair as needed and retest.
- If wiring and heater are good but the downstream sensor shows minimal/very slow change, replace the downstream O2 sensor (Bank 1 Sensor 2). After replacement, clear codes and perform drive cycle to confirm monitor completion.
- If new sensor does not restore normal behavior, evaluate catalytic converter efficiency and PCM operation; perform catalyst temperature/pressure tests or consult manufacturer service data.
- Note: follow OEM safety and immobilizer procedures; avoid open exhaust while hot and use vehicle‑specific test values when available.
Likely causes
- Contaminated or worn downstream O2 sensor
- Faulty heater element or heater circuit for Bank 1 Sensor 2
- Corroded/damaged sensor connector or broken wiring
- Exhaust leak between catalyst and sensor affecting readings
Fault status
Status
Downstream O2 sensor (Bank 1 Sensor 2) response is slower than expected during catalyst monitor — monitor failed.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
P1197
JEEP
P — Powertrain
O2 Sensor 1/2 (Bank 1 Sensor 2) Slow During Catalyst Monitor
Views:
UK: 16
EN: 23
RU: 24
AI status
Completed
Completed
100%
Causes
- Aging or contaminated downstream O2 sensor (Bank 1 Sensor 2)
- Heater circuit open/weak or slow to reach operating temperature
- Damaged wiring, corroded connector pins, or poor ground to the sensor
- Exhaust leaks upstream of the sensor altering signal behavior
- Plugged or failing catalytic converter changing post‑cat response
- Engine running issues (fuel trim extremes, misfire) affecting exhaust composition
Symptoms
- Check Engine Light (MIL) illuminated and readiness monitor failed for catalyst
- Failed catalyst/catalyst monitor on vehicle inspection
- Poor fuel economy or increased emissions (may be subtle)
- Possible rough idle or drivability complaints if sensor/heater or engine condition is affecting closed‑loop control
What to check
- Read DTCs and freeze‑frame data with a full‑function scan tool
- Verify readiness and catalyst monitor status
- Inspect sensor connector and wiring for corrosion, damage, or loose pins
- Monitor live O2 sensor voltages for Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) while engine warms and during induced rich/lean events
- Confirm downstream sensor response time versus upstream sensor: downstream should be less switching but should show change after fuel/AFR step
- Check heater supply voltage and ground at connector with ignition on; measure heater resistance with sensor disconnected
Signal parameters
- Upstream narrowband O2 (Bank 1 Sensor 1): rapid switching approximately 0.1–0.9 V when in closed loop
- Downstream O2 (Bank 1 Sensor 2): should be relatively steady compared to upstream but must still show response to deliberate rich/lean changes (small voltage shift)
- Expected downstream response: a measurable change in voltage within a few seconds after induced exhaust composition change
- Heater circuit: supply voltage near battery voltage with ignition on; heater resistance typically low (varies by sensor, commonly single‑digit to low tens of ohms)
Diagnostic algorithm
- Confirm P1197 present and note freeze frame and related codes. Clear code and attempt a drive cycle to reproduce.
- Visual inspection: check Bank 1 Sensor 2 connector for corrosion, water intrusion, broken wires, or poor grounds. Repair any damage.
- With scan tool, observe Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) voltages during warm idle and during commanded rich/lean events (throttle blips or induced fuel trim changes). Downstream should change within seconds.
- Test heater circuit: with ignition off disconnect sensor and measure heater resistance; compare to spec or typical range. With ignition on, verify reference voltage/power to heater and good ground.
- Check for exhaust leaks between catalyst and downstream sensor; repair as needed and retest.
- If wiring and heater are good but the downstream sensor shows minimal/very slow change, replace the downstream O2 sensor (Bank 1 Sensor 2). After replacement, clear codes and perform drive cycle to confirm monitor completion.
- If new sensor does not restore normal behavior, evaluate catalytic converter efficiency and PCM operation; perform catalyst temperature/pressure tests or consult manufacturer service data.
- Note: follow OEM safety and immobilizer procedures; avoid open exhaust while hot and use vehicle‑specific test values when available.
Likely causes
- Contaminated or worn downstream O2 sensor
- Faulty heater element or heater circuit for Bank 1 Sensor 2
- Corroded/damaged sensor connector or broken wiring
- Exhaust leak between catalyst and sensor affecting readings
Fault status
Status
Downstream O2 sensor (Bank 1 Sensor 2) response is slower than expected during catalyst monitor — monitor failed.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
P1197
LINCOLN
P — Powertrain
Key Off Voltage Low
Views:
UK: 13
EN: 21
RU: 26
AI status
Completed
Completed
100%
Causes
- Aging or contaminated downstream O2 sensor (Bank 1 Sensor 2)
- Heater circuit open/weak or slow to reach operating temperature
- Damaged wiring, corroded connector pins, or poor ground to the sensor
- Exhaust leaks upstream of the sensor altering signal behavior
- Plugged or failing catalytic converter changing post‑cat response
- Engine running issues (fuel trim extremes, misfire) affecting exhaust composition
Symptoms
- Check Engine Light (MIL) illuminated and readiness monitor failed for catalyst
- Failed catalyst/catalyst monitor on vehicle inspection
- Poor fuel economy or increased emissions (may be subtle)
- Possible rough idle or drivability complaints if sensor/heater or engine condition is affecting closed‑loop control
What to check
- Read DTCs and freeze‑frame data with a full‑function scan tool
- Verify readiness and catalyst monitor status
- Inspect sensor connector and wiring for corrosion, damage, or loose pins
- Monitor live O2 sensor voltages for Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) while engine warms and during induced rich/lean events
- Confirm downstream sensor response time versus upstream sensor: downstream should be less switching but should show change after fuel/AFR step
- Check heater supply voltage and ground at connector with ignition on; measure heater resistance with sensor disconnected
Signal parameters
- Upstream narrowband O2 (Bank 1 Sensor 1): rapid switching approximately 0.1–0.9 V when in closed loop
- Downstream O2 (Bank 1 Sensor 2): should be relatively steady compared to upstream but must still show response to deliberate rich/lean changes (small voltage shift)
- Expected downstream response: a measurable change in voltage within a few seconds after induced exhaust composition change
- Heater circuit: supply voltage near battery voltage with ignition on; heater resistance typically low (varies by sensor, commonly single‑digit to low tens of ohms)
Diagnostic algorithm
- Confirm P1197 present and note freeze frame and related codes. Clear code and attempt a drive cycle to reproduce.
- Visual inspection: check Bank 1 Sensor 2 connector for corrosion, water intrusion, broken wires, or poor grounds. Repair any damage.
- With scan tool, observe Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) voltages during warm idle and during commanded rich/lean events (throttle blips or induced fuel trim changes). Downstream should change within seconds.
- Test heater circuit: with ignition off disconnect sensor and measure heater resistance; compare to spec or typical range. With ignition on, verify reference voltage/power to heater and good ground.
- Check for exhaust leaks between catalyst and downstream sensor; repair as needed and retest.
- If wiring and heater are good but the downstream sensor shows minimal/very slow change, replace the downstream O2 sensor (Bank 1 Sensor 2). After replacement, clear codes and perform drive cycle to confirm monitor completion.
- If new sensor does not restore normal behavior, evaluate catalytic converter efficiency and PCM operation; perform catalyst temperature/pressure tests or consult manufacturer service data.
- Note: follow OEM safety and immobilizer procedures; avoid open exhaust while hot and use vehicle‑specific test values when available.
Likely causes
- Contaminated or worn downstream O2 sensor
- Faulty heater element or heater circuit for Bank 1 Sensor 2
- Corroded/damaged sensor connector or broken wiring
- Exhaust leak between catalyst and sensor affecting readings
Fault status
Status
Downstream O2 sensor (Bank 1 Sensor 2) response is slower than expected during catalyst monitor — monitor failed.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
P1197
MAZDA
P — Powertrain
Mileage Switch Circuit
Views:
UK: 11
EN: 18
RU: 23
AI status
Completed
Completed
100%
Causes
- Aging or contaminated downstream O2 sensor (Bank 1 Sensor 2)
- Heater circuit open/weak or slow to reach operating temperature
- Damaged wiring, corroded connector pins, or poor ground to the sensor
- Exhaust leaks upstream of the sensor altering signal behavior
- Plugged or failing catalytic converter changing post‑cat response
- Engine running issues (fuel trim extremes, misfire) affecting exhaust composition
Symptoms
- Check Engine Light (MIL) illuminated and readiness monitor failed for catalyst
- Failed catalyst/catalyst monitor on vehicle inspection
- Poor fuel economy or increased emissions (may be subtle)
- Possible rough idle or drivability complaints if sensor/heater or engine condition is affecting closed‑loop control
What to check
- Read DTCs and freeze‑frame data with a full‑function scan tool
- Verify readiness and catalyst monitor status
- Inspect sensor connector and wiring for corrosion, damage, or loose pins
- Monitor live O2 sensor voltages for Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) while engine warms and during induced rich/lean events
- Confirm downstream sensor response time versus upstream sensor: downstream should be less switching but should show change after fuel/AFR step
- Check heater supply voltage and ground at connector with ignition on; measure heater resistance with sensor disconnected
Signal parameters
- Upstream narrowband O2 (Bank 1 Sensor 1): rapid switching approximately 0.1–0.9 V when in closed loop
- Downstream O2 (Bank 1 Sensor 2): should be relatively steady compared to upstream but must still show response to deliberate rich/lean changes (small voltage shift)
- Expected downstream response: a measurable change in voltage within a few seconds after induced exhaust composition change
- Heater circuit: supply voltage near battery voltage with ignition on; heater resistance typically low (varies by sensor, commonly single‑digit to low tens of ohms)
Diagnostic algorithm
- Confirm P1197 present and note freeze frame and related codes. Clear code and attempt a drive cycle to reproduce.
- Visual inspection: check Bank 1 Sensor 2 connector for corrosion, water intrusion, broken wires, or poor grounds. Repair any damage.
- With scan tool, observe Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) voltages during warm idle and during commanded rich/lean events (throttle blips or induced fuel trim changes). Downstream should change within seconds.
- Test heater circuit: with ignition off disconnect sensor and measure heater resistance; compare to spec or typical range. With ignition on, verify reference voltage/power to heater and good ground.
- Check for exhaust leaks between catalyst and downstream sensor; repair as needed and retest.
- If wiring and heater are good but the downstream sensor shows minimal/very slow change, replace the downstream O2 sensor (Bank 1 Sensor 2). After replacement, clear codes and perform drive cycle to confirm monitor completion.
- If new sensor does not restore normal behavior, evaluate catalytic converter efficiency and PCM operation; perform catalyst temperature/pressure tests or consult manufacturer service data.
- Note: follow OEM safety and immobilizer procedures; avoid open exhaust while hot and use vehicle‑specific test values when available.
Likely causes
- Contaminated or worn downstream O2 sensor
- Faulty heater element or heater circuit for Bank 1 Sensor 2
- Corroded/damaged sensor connector or broken wiring
- Exhaust leak between catalyst and sensor affecting readings
Fault status
Status
Downstream O2 sensor (Bank 1 Sensor 2) response is slower than expected during catalyst monitor — monitor failed.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
P1197
MERCURY
P — Powertrain
Key Off Voltage Low
Views:
UK: 15
EN: 23
RU: 20
AI status
Completed
Completed
100%
Causes
- Aging or contaminated downstream O2 sensor (Bank 1 Sensor 2)
- Heater circuit open/weak or slow to reach operating temperature
- Damaged wiring, corroded connector pins, or poor ground to the sensor
- Exhaust leaks upstream of the sensor altering signal behavior
- Plugged or failing catalytic converter changing post‑cat response
- Engine running issues (fuel trim extremes, misfire) affecting exhaust composition
Symptoms
- Check Engine Light (MIL) illuminated and readiness monitor failed for catalyst
- Failed catalyst/catalyst monitor on vehicle inspection
- Poor fuel economy or increased emissions (may be subtle)
- Possible rough idle or drivability complaints if sensor/heater or engine condition is affecting closed‑loop control
What to check
- Read DTCs and freeze‑frame data with a full‑function scan tool
- Verify readiness and catalyst monitor status
- Inspect sensor connector and wiring for corrosion, damage, or loose pins
- Monitor live O2 sensor voltages for Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) while engine warms and during induced rich/lean events
- Confirm downstream sensor response time versus upstream sensor: downstream should be less switching but should show change after fuel/AFR step
- Check heater supply voltage and ground at connector with ignition on; measure heater resistance with sensor disconnected
Signal parameters
- Upstream narrowband O2 (Bank 1 Sensor 1): rapid switching approximately 0.1–0.9 V when in closed loop
- Downstream O2 (Bank 1 Sensor 2): should be relatively steady compared to upstream but must still show response to deliberate rich/lean changes (small voltage shift)
- Expected downstream response: a measurable change in voltage within a few seconds after induced exhaust composition change
- Heater circuit: supply voltage near battery voltage with ignition on; heater resistance typically low (varies by sensor, commonly single‑digit to low tens of ohms)
Diagnostic algorithm
- Confirm P1197 present and note freeze frame and related codes. Clear code and attempt a drive cycle to reproduce.
- Visual inspection: check Bank 1 Sensor 2 connector for corrosion, water intrusion, broken wires, or poor grounds. Repair any damage.
- With scan tool, observe Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) voltages during warm idle and during commanded rich/lean events (throttle blips or induced fuel trim changes). Downstream should change within seconds.
- Test heater circuit: with ignition off disconnect sensor and measure heater resistance; compare to spec or typical range. With ignition on, verify reference voltage/power to heater and good ground.
- Check for exhaust leaks between catalyst and downstream sensor; repair as needed and retest.
- If wiring and heater are good but the downstream sensor shows minimal/very slow change, replace the downstream O2 sensor (Bank 1 Sensor 2). After replacement, clear codes and perform drive cycle to confirm monitor completion.
- If new sensor does not restore normal behavior, evaluate catalytic converter efficiency and PCM operation; perform catalyst temperature/pressure tests or consult manufacturer service data.
- Note: follow OEM safety and immobilizer procedures; avoid open exhaust while hot and use vehicle‑specific test values when available.
Likely causes
- Contaminated or worn downstream O2 sensor
- Faulty heater element or heater circuit for Bank 1 Sensor 2
- Corroded/damaged sensor connector or broken wiring
- Exhaust leak between catalyst and sensor affecting readings
Fault status
Status
Downstream O2 sensor (Bank 1 Sensor 2) response is slower than expected during catalyst monitor — monitor failed.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
P1197
Other
P — Powertrain
Key Off Voltage Low
Views:
UK: 13
EN: 24
RU: 22
AI status
Completed
Completed
100%
Causes
- Aging or contaminated downstream O2 sensor (Bank 1 Sensor 2)
- Heater circuit open/weak or slow to reach operating temperature
- Damaged wiring, corroded connector pins, or poor ground to the sensor
- Exhaust leaks upstream of the sensor altering signal behavior
- Plugged or failing catalytic converter changing post‑cat response
- Engine running issues (fuel trim extremes, misfire) affecting exhaust composition
Symptoms
- Check Engine Light (MIL) illuminated and readiness monitor failed for catalyst
- Failed catalyst/catalyst monitor on vehicle inspection
- Poor fuel economy or increased emissions (may be subtle)
- Possible rough idle or drivability complaints if sensor/heater or engine condition is affecting closed‑loop control
What to check
- Read DTCs and freeze‑frame data with a full‑function scan tool
- Verify readiness and catalyst monitor status
- Inspect sensor connector and wiring for corrosion, damage, or loose pins
- Monitor live O2 sensor voltages for Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) while engine warms and during induced rich/lean events
- Confirm downstream sensor response time versus upstream sensor: downstream should be less switching but should show change after fuel/AFR step
- Check heater supply voltage and ground at connector with ignition on; measure heater resistance with sensor disconnected
Signal parameters
- Upstream narrowband O2 (Bank 1 Sensor 1): rapid switching approximately 0.1–0.9 V when in closed loop
- Downstream O2 (Bank 1 Sensor 2): should be relatively steady compared to upstream but must still show response to deliberate rich/lean changes (small voltage shift)
- Expected downstream response: a measurable change in voltage within a few seconds after induced exhaust composition change
- Heater circuit: supply voltage near battery voltage with ignition on; heater resistance typically low (varies by sensor, commonly single‑digit to low tens of ohms)
Diagnostic algorithm
- Confirm P1197 present and note freeze frame and related codes. Clear code and attempt a drive cycle to reproduce.
- Visual inspection: check Bank 1 Sensor 2 connector for corrosion, water intrusion, broken wires, or poor grounds. Repair any damage.
- With scan tool, observe Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) voltages during warm idle and during commanded rich/lean events (throttle blips or induced fuel trim changes). Downstream should change within seconds.
- Test heater circuit: with ignition off disconnect sensor and measure heater resistance; compare to spec or typical range. With ignition on, verify reference voltage/power to heater and good ground.
- Check for exhaust leaks between catalyst and downstream sensor; repair as needed and retest.
- If wiring and heater are good but the downstream sensor shows minimal/very slow change, replace the downstream O2 sensor (Bank 1 Sensor 2). After replacement, clear codes and perform drive cycle to confirm monitor completion.
- If new sensor does not restore normal behavior, evaluate catalytic converter efficiency and PCM operation; perform catalyst temperature/pressure tests or consult manufacturer service data.
- Note: follow OEM safety and immobilizer procedures; avoid open exhaust while hot and use vehicle‑specific test values when available.
Likely causes
- Contaminated or worn downstream O2 sensor
- Faulty heater element or heater circuit for Bank 1 Sensor 2
- Corroded/damaged sensor connector or broken wiring
- Exhaust leak between catalyst and sensor affecting readings
Fault status
Status
Downstream O2 sensor (Bank 1 Sensor 2) response is slower than expected during catalyst monitor — monitor failed.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
P1197
PLYMOUTH
P — Powertrain
O2 Sensor 1/2 (Bank 1 Sensor 2) Slow During Catalyst Monitor
Views:
UK: 17
EN: 30
RU: 27
AI status
Completed
Completed
100%
Causes
- Aging or contaminated downstream O2 sensor (Bank 1 Sensor 2)
- Heater circuit open/weak or slow to reach operating temperature
- Damaged wiring, corroded connector pins, or poor ground to the sensor
- Exhaust leaks upstream of the sensor altering signal behavior
- Plugged or failing catalytic converter changing post‑cat response
- Engine running issues (fuel trim extremes, misfire) affecting exhaust composition
Symptoms
- Check Engine Light (MIL) illuminated and readiness monitor failed for catalyst
- Failed catalyst/catalyst monitor on vehicle inspection
- Poor fuel economy or increased emissions (may be subtle)
- Possible rough idle or drivability complaints if sensor/heater or engine condition is affecting closed‑loop control
What to check
- Read DTCs and freeze‑frame data with a full‑function scan tool
- Verify readiness and catalyst monitor status
- Inspect sensor connector and wiring for corrosion, damage, or loose pins
- Monitor live O2 sensor voltages for Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) while engine warms and during induced rich/lean events
- Confirm downstream sensor response time versus upstream sensor: downstream should be less switching but should show change after fuel/AFR step
- Check heater supply voltage and ground at connector with ignition on; measure heater resistance with sensor disconnected
Signal parameters
- Upstream narrowband O2 (Bank 1 Sensor 1): rapid switching approximately 0.1–0.9 V when in closed loop
- Downstream O2 (Bank 1 Sensor 2): should be relatively steady compared to upstream but must still show response to deliberate rich/lean changes (small voltage shift)
- Expected downstream response: a measurable change in voltage within a few seconds after induced exhaust composition change
- Heater circuit: supply voltage near battery voltage with ignition on; heater resistance typically low (varies by sensor, commonly single‑digit to low tens of ohms)
Diagnostic algorithm
- Confirm P1197 present and note freeze frame and related codes. Clear code and attempt a drive cycle to reproduce.
- Visual inspection: check Bank 1 Sensor 2 connector for corrosion, water intrusion, broken wires, or poor grounds. Repair any damage.
- With scan tool, observe Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) voltages during warm idle and during commanded rich/lean events (throttle blips or induced fuel trim changes). Downstream should change within seconds.
- Test heater circuit: with ignition off disconnect sensor and measure heater resistance; compare to spec or typical range. With ignition on, verify reference voltage/power to heater and good ground.
- Check for exhaust leaks between catalyst and downstream sensor; repair as needed and retest.
- If wiring and heater are good but the downstream sensor shows minimal/very slow change, replace the downstream O2 sensor (Bank 1 Sensor 2). After replacement, clear codes and perform drive cycle to confirm monitor completion.
- If new sensor does not restore normal behavior, evaluate catalytic converter efficiency and PCM operation; perform catalyst temperature/pressure tests or consult manufacturer service data.
- Note: follow OEM safety and immobilizer procedures; avoid open exhaust while hot and use vehicle‑specific test values when available.
Likely causes
- Contaminated or worn downstream O2 sensor
- Faulty heater element or heater circuit for Bank 1 Sensor 2
- Corroded/damaged sensor connector or broken wiring
- Exhaust leak between catalyst and sensor affecting readings
Fault status
Status
Downstream O2 sensor (Bank 1 Sensor 2) response is slower than expected during catalyst monitor — monitor failed.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
P1197
PONTIAC
P — Powertrain
O2 Sensor 1/2 (Bank 1 Sensor 2) Slow During Catalyst Monitor
Views:
UK: 15
EN: 26
RU: 25
AI status
Completed
Completed
100%
Causes
- Aging or contaminated downstream O2 sensor (Bank 1 Sensor 2)
- Heater circuit open/weak or slow to reach operating temperature
- Damaged wiring, corroded connector pins, or poor ground to the sensor
- Exhaust leaks upstream of the sensor altering signal behavior
- Plugged or failing catalytic converter changing post‑cat response
- Engine running issues (fuel trim extremes, misfire) affecting exhaust composition
Symptoms
- Check Engine Light (MIL) illuminated and readiness monitor failed for catalyst
- Failed catalyst/catalyst monitor on vehicle inspection
- Poor fuel economy or increased emissions (may be subtle)
- Possible rough idle or drivability complaints if sensor/heater or engine condition is affecting closed‑loop control
What to check
- Read DTCs and freeze‑frame data with a full‑function scan tool
- Verify readiness and catalyst monitor status
- Inspect sensor connector and wiring for corrosion, damage, or loose pins
- Monitor live O2 sensor voltages for Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) while engine warms and during induced rich/lean events
- Confirm downstream sensor response time versus upstream sensor: downstream should be less switching but should show change after fuel/AFR step
- Check heater supply voltage and ground at connector with ignition on; measure heater resistance with sensor disconnected
Signal parameters
- Upstream narrowband O2 (Bank 1 Sensor 1): rapid switching approximately 0.1–0.9 V when in closed loop
- Downstream O2 (Bank 1 Sensor 2): should be relatively steady compared to upstream but must still show response to deliberate rich/lean changes (small voltage shift)
- Expected downstream response: a measurable change in voltage within a few seconds after induced exhaust composition change
- Heater circuit: supply voltage near battery voltage with ignition on; heater resistance typically low (varies by sensor, commonly single‑digit to low tens of ohms)
Diagnostic algorithm
- Confirm P1197 present and note freeze frame and related codes. Clear code and attempt a drive cycle to reproduce.
- Visual inspection: check Bank 1 Sensor 2 connector for corrosion, water intrusion, broken wires, or poor grounds. Repair any damage.
- With scan tool, observe Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) voltages during warm idle and during commanded rich/lean events (throttle blips or induced fuel trim changes). Downstream should change within seconds.
- Test heater circuit: with ignition off disconnect sensor and measure heater resistance; compare to spec or typical range. With ignition on, verify reference voltage/power to heater and good ground.
- Check for exhaust leaks between catalyst and downstream sensor; repair as needed and retest.
- If wiring and heater are good but the downstream sensor shows minimal/very slow change, replace the downstream O2 sensor (Bank 1 Sensor 2). After replacement, clear codes and perform drive cycle to confirm monitor completion.
- If new sensor does not restore normal behavior, evaluate catalytic converter efficiency and PCM operation; perform catalyst temperature/pressure tests or consult manufacturer service data.
- Note: follow OEM safety and immobilizer procedures; avoid open exhaust while hot and use vehicle‑specific test values when available.
Likely causes
- Contaminated or worn downstream O2 sensor
- Faulty heater element or heater circuit for Bank 1 Sensor 2
- Corroded/damaged sensor connector or broken wiring
- Exhaust leak between catalyst and sensor affecting readings
Fault status
Status
Downstream O2 sensor (Bank 1 Sensor 2) response is slower than expected during catalyst monitor — monitor failed.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
P1197
RAM
P — Powertrain
Slow Switching O2 Sensor Bank One Sensor two During catalyst monitoring
Views:
UK: 2
EN: 4
RU: 1
AI status
Completed
Completed
100%
Causes
- Aging or contaminated downstream O2 sensor (Bank 1 Sensor 2)
- Heater circuit open/weak or slow to reach operating temperature
- Damaged wiring, corroded connector pins, or poor ground to the sensor
- Exhaust leaks upstream of the sensor altering signal behavior
- Plugged or failing catalytic converter changing post‑cat response
- Engine running issues (fuel trim extremes, misfire) affecting exhaust composition
Symptoms
- Check Engine Light (MIL) illuminated and readiness monitor failed for catalyst
- Failed catalyst/catalyst monitor on vehicle inspection
- Poor fuel economy or increased emissions (may be subtle)
- Possible rough idle or drivability complaints if sensor/heater or engine condition is affecting closed‑loop control
What to check
- Read DTCs and freeze‑frame data with a full‑function scan tool
- Verify readiness and catalyst monitor status
- Inspect sensor connector and wiring for corrosion, damage, or loose pins
- Monitor live O2 sensor voltages for Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) while engine warms and during induced rich/lean events
- Confirm downstream sensor response time versus upstream sensor: downstream should be less switching but should show change after fuel/AFR step
- Check heater supply voltage and ground at connector with ignition on; measure heater resistance with sensor disconnected
Signal parameters
- Upstream narrowband O2 (Bank 1 Sensor 1): rapid switching approximately 0.1–0.9 V when in closed loop
- Downstream O2 (Bank 1 Sensor 2): should be relatively steady compared to upstream but must still show response to deliberate rich/lean changes (small voltage shift)
- Expected downstream response: a measurable change in voltage within a few seconds after induced exhaust composition change
- Heater circuit: supply voltage near battery voltage with ignition on; heater resistance typically low (varies by sensor, commonly single‑digit to low tens of ohms)
Diagnostic algorithm
- Confirm P1197 present and note freeze frame and related codes. Clear code and attempt a drive cycle to reproduce.
- Visual inspection: check Bank 1 Sensor 2 connector for corrosion, water intrusion, broken wires, or poor grounds. Repair any damage.
- With scan tool, observe Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) voltages during warm idle and during commanded rich/lean events (throttle blips or induced fuel trim changes). Downstream should change within seconds.
- Test heater circuit: with ignition off disconnect sensor and measure heater resistance; compare to spec or typical range. With ignition on, verify reference voltage/power to heater and good ground.
- Check for exhaust leaks between catalyst and downstream sensor; repair as needed and retest.
- If wiring and heater are good but the downstream sensor shows minimal/very slow change, replace the downstream O2 sensor (Bank 1 Sensor 2). After replacement, clear codes and perform drive cycle to confirm monitor completion.
- If new sensor does not restore normal behavior, evaluate catalytic converter efficiency and PCM operation; perform catalyst temperature/pressure tests or consult manufacturer service data.
- Note: follow OEM safety and immobilizer procedures; avoid open exhaust while hot and use vehicle‑specific test values when available.
Likely causes
- Contaminated or worn downstream O2 sensor
- Faulty heater element or heater circuit for Bank 1 Sensor 2
- Corroded/damaged sensor connector or broken wiring
- Exhaust leak between catalyst and sensor affecting readings
Fault status
Status
Downstream O2 sensor (Bank 1 Sensor 2) response is slower than expected during catalyst monitor — monitor failed.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
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+100 karma for a short comment :)
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Code
P1197
VOLKSWAGEN
P — Powertrain
Oxygen Sensor Heater Circuit Bank 2 Sensor 1 Electrical Malfunction
Views:
UK: 13
EN: 26
RU: 24
AI status
Completed
Completed
100%
Causes
- Aging or contaminated downstream O2 sensor (Bank 1 Sensor 2)
- Heater circuit open/weak or slow to reach operating temperature
- Damaged wiring, corroded connector pins, or poor ground to the sensor
- Exhaust leaks upstream of the sensor altering signal behavior
- Plugged or failing catalytic converter changing post‑cat response
- Engine running issues (fuel trim extremes, misfire) affecting exhaust composition
Symptoms
- Check Engine Light (MIL) illuminated and readiness monitor failed for catalyst
- Failed catalyst/catalyst monitor on vehicle inspection
- Poor fuel economy or increased emissions (may be subtle)
- Possible rough idle or drivability complaints if sensor/heater or engine condition is affecting closed‑loop control
What to check
- Read DTCs and freeze‑frame data with a full‑function scan tool
- Verify readiness and catalyst monitor status
- Inspect sensor connector and wiring for corrosion, damage, or loose pins
- Monitor live O2 sensor voltages for Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) while engine warms and during induced rich/lean events
- Confirm downstream sensor response time versus upstream sensor: downstream should be less switching but should show change after fuel/AFR step
- Check heater supply voltage and ground at connector with ignition on; measure heater resistance with sensor disconnected
Signal parameters
- Upstream narrowband O2 (Bank 1 Sensor 1): rapid switching approximately 0.1–0.9 V when in closed loop
- Downstream O2 (Bank 1 Sensor 2): should be relatively steady compared to upstream but must still show response to deliberate rich/lean changes (small voltage shift)
- Expected downstream response: a measurable change in voltage within a few seconds after induced exhaust composition change
- Heater circuit: supply voltage near battery voltage with ignition on; heater resistance typically low (varies by sensor, commonly single‑digit to low tens of ohms)
Diagnostic algorithm
- Confirm P1197 present and note freeze frame and related codes. Clear code and attempt a drive cycle to reproduce.
- Visual inspection: check Bank 1 Sensor 2 connector for corrosion, water intrusion, broken wires, or poor grounds. Repair any damage.
- With scan tool, observe Bank 1 Sensor 1 (upstream) and Bank 1 Sensor 2 (downstream) voltages during warm idle and during commanded rich/lean events (throttle blips or induced fuel trim changes). Downstream should change within seconds.
- Test heater circuit: with ignition off disconnect sensor and measure heater resistance; compare to spec or typical range. With ignition on, verify reference voltage/power to heater and good ground.
- Check for exhaust leaks between catalyst and downstream sensor; repair as needed and retest.
- If wiring and heater are good but the downstream sensor shows minimal/very slow change, replace the downstream O2 sensor (Bank 1 Sensor 2). After replacement, clear codes and perform drive cycle to confirm monitor completion.
- If new sensor does not restore normal behavior, evaluate catalytic converter efficiency and PCM operation; perform catalyst temperature/pressure tests or consult manufacturer service data.
- Note: follow OEM safety and immobilizer procedures; avoid open exhaust while hot and use vehicle‑specific test values when available.
Likely causes
- Contaminated or worn downstream O2 sensor
- Faulty heater element or heater circuit for Bank 1 Sensor 2
- Corroded/damaged sensor connector or broken wiring
- Exhaust leak between catalyst and sensor affecting readings
Fault status
Status
Downstream O2 sensor (Bank 1 Sensor 2) response is slower than expected during catalyst monitor — monitor failed.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email