The code P0141: O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2) points out a fault in the oxygen sensor heater circuit, and most likely is caused by a malfunctioning O2 sensor or issues in the wiring and connections.
P0141 quick overview
| Meaning | P0141: O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2) |
| Is it serious? | Yes, it can affect fuel efficiency, emissions, and overall engine performance. |
| Possible causes | – Faulty or malfunctioning O2 sensor – Damaged or broken wiring to the O2 sensor – Water intrusion or contamination in O2 sensor connectors – Faulty relay or fuse related to the O2 sensor heater circuit – Malfunctioning Engine Control Module (ECM) |
| How to diagnose? | Scan the vehicle: Use a diagnostic scanner to read and confirm the fault code. Check the O2 sensor voltages: Monitor the voltage of the O2 sensors using a scanner or multimeter. Inspect the O2 sensors: Physically examine the sensors for any visible damage or contamination. Examine wiring and connections: Check for any broken wires, water intrusion, or other issues in the sensor connectors. Test the O2 sensor heater: Monitor the heater’s performance, especially during cold starts, to ensure it’s functioning correctly. Check fuel pressure: Ensure that the fuel pressure is within the specified range, as it can influence O2 sensor readings. Consider the ECM: If all else seems fine, consider the possibility of a malfunctioning Engine Control Module. |
| What is Bank 1 Sensor 2? | Post-cat oxygen sensor for engine head 1. Read the full Bank1 vs Bank2 explanation. |
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How to fix P0141 – learn from mechanics
I looked into P0141 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics.I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Chevrolet
Vehicle Information:
- 2001 Chevrolet Impala, 3.4L Engine
Issue + Repair History:
- MIL (Malfunction Indicator Lamp) activated.
- Codes: p041 (b1-s2 o2 sensor heater circuit malfunction) and p0141 (o2 sensor b1-s2 heater circuit malfunction).
- Replaced rear oxygen sensor and cleared the code.
- After 3 days, 3 monitors including o2 heater did not reset.
- Found p0141 in pending but no MIL activated.
- Checked power and ground to O2 sensor, both were okay.
- Two wires (tan and purple) related to the O2 sensor showed no voltage or ground.
Community Suggestions:
- Test the sensor heater according to the service manual procedure.
- Check continuity to PCM; if okay, the issue might be in the ECM.
- Ensure using a Delco O2 sensor as aftermarket sensors can cause issues.
- Consider the possibility of needing a new catalytic converter.
- Check plug harness wires that run to PCM; the aluminum shield might accumulate dirt, causing wires to wear and break.
- Check for broken wires in the wiring harness.
Final Fix:
- The PCM (Powertrain Control Module) was defective. Replaced the PCM and resolved the issue.
Case #2: Nissan
Vehicle Information:
- 2001 Nissan Xterra SE, 3.3L Engine
Issue + Repair History:
- MIL (Malfunction Indicator Lamp) activated.
- O2 sensor b1s1 had a fixed value at times, but the problem was intermittent and couldn’t be duplicated in the shop.
- Replaced the O2 sensor with a new one.
Community Suggestions:
- Check the code definition; p0141 might be related to the heater circuit for bank 1 sensor 2.
- Ensure accurate code diagnosis.
- Check the O2 sensor signal at the sensor with a scope. Some Japanese vehicles might not show a waveform at idle.
- Verify the O2 sensor signal while driving the vehicle and compare readings between the scanner and scope.
- Consider a computer reflash to address the issue.
Final Fix:
- Reflashing the computer resolved the problem. The vehicle was taken to the Nissan dealer for the reflash.
Case #3: Kia
Vehicle Information:
- 1999 Kia Sportage, 2.0L Engine
Issue + Repair History:
- MIL (Malfunction Indicator Lamp) activated.
- Initial codes were P0135 and P0141.
- Both O2 sensors were replaced twice.
- While waiting for new O2 sensors from the dealer, all fuses, connections, and grounds between the computer and the sensors were checked.
- No broken wires were found.
- The computer wasn’t commanding the O2 sensor heaters on, leading to the replacement of the computer.
- After replacing the computer, new pending codes appeared: P0134, P0135, P0140, and P0141.
- Despite the new codes, the vehicle achieved closed loop faster and showed good O2 readings on the scanner.
Community Suggestions:
- Check the heater fuses.
Final Fix:
- The issue was resolved by replacing the fuel pump relay.
Case #4: Mercedes
- 2001 Mercedes-Benz CL500, 5.0L Engine
Issue + Repair History:
- MIL (Malfunction Indicator Lamp) activated.
- No drivability issues observed.
- All sensors showed 12v & ground for the heaters to function.
- All heaters measured 2.5 ohms.
- All O2 sensors were replaced.
Community Suggestions:
- Check the amperage draw, which should be between 0.5-2.0 amperes.
- Consider the possibility of poor flow through the exhaust.
- Ensure the sensors are original as there are different wattages.
- The ECU might be faulty.
Final Fix:
- The vehicle was sent to the dealer, and the issue was identified as a faulty ECM
Case #5: Chevrolet
Vehicle Information:
- 1997 Chevrolet Blazer, 4.3L Engine
Issue + Repair History:
- MIL (Malfunction Indicator Lamp) activated.
- Two codes for HO2S B1S1 and B1S2 were detected.
- Checked TSBs and circuits, all appeared good.
- Removed sensors, which looked okay with no contamination and good connections.
- Sensors switched normally and VCM entered closed loop in 1 minute.
- Replaced both O2 sensors twice.
- Replaced the computer.
Community Suggestions:
- Observe O2 sensor voltages with the scanner.
- Check fuel pressure and ensure it’s within specification.
- Ensure the sensors are original.
- Monitor the heater of the sensor for the PO141 code with a cold engine.
- Consider switching sensors from one side to another to see if the code switches.
- Use a scope to test the activity monitor and compare with a known good one.
Final Fix:
- Replaced both O2 sensors and the problem was resolved. It was suspicious that two sensors on the same bank went bad at the same time.
How to diagnose P0141
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Advice | Brief Description of Diagnostic Step |
|---|---|
| Check O2 sensor voltages | Monitor the voltage of the O2 sensors using a scanner. |
| Replace O2 sensors | If there are suspicions or indications, consider replacing the O2 sensors, even if they seem to be functioning correctly. |
| Check fuel pressure | Ensure that the fuel pressure is within the specified range. |
| Examine sensor wiring and connections | Look for any broken wires, water intrusion, or other issues in the sensor connectors. |
| Monitor heater of the sensor | For codes related to heater circuits, observe the heater’s performance, especially during cold starts. |
| Consider computer/ECM issues | In some cases, the issue might be with the Engine Control Module (ECM) or computer, not the sensors themselves. |
| Check for proper sensor type | Ensure that the sensors being used are the original or correct type for the vehicle. |
Car Diagnostics Training
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- OBD-II scanner basics
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I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko