DTC Troubleshooting

DTC Troubleshooting: P0141

DTC P0141: Secondary HO2S (Sensor 2) Heater Circuit Malfunction

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information. Reading and Clearing Diagnostic Trouble Codes

1. Turn the ignition switch to ON (II).

2. Clear the DTC with the HDS.

3. Start the engine.

4. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0141 indicated?
YES - Go to step 5.

NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the ECM/PCM.


5. Turn the ignition switch to LOCK (0).

6. Check the No. 3 ALTERNATOR (10 A) fuse in the under-dash fuse/relay box.

Is the fuse OK?
YES - Go to step 7.

NO - Repair short in the No. 3 ALTERNATOR (10 A) fuse circuit. Also replace the No. 3 ALTERNATOR (10 A) fuse, then go to step 22.


7. Disconnect the secondary HO2S (Sensor 2) 4P connector.

8. At the sensor side, measure the resistance between secondary HO2S (Sensor 2) 4P connector terminals No. 3 and No. 4.

Is there 5.4-7.3 Ohms at room temperature?
YES - Go to step 9.

NO - Go to step 21.






9. At the sensor side, check for continuity between body ground and secondary HO2S (Sensor 2) 4P connector terminals No. 3 and No. 4 individually.

Is there continuity?
YES - Go to step 21.

NO - Go to step 10.






10. Turn the ignition switch to ON (II).

11. Measure the voltage between secondary HO2S (Sensor 2) 4P connector terminals No. 3 and No. 4.

Is there battery voltage?
YES - Go to step 12.

NO - Go to step 16.






12. Turn the ignition switch to LOCK (0).

13. Jump the SCS line with the HDS.

14. Disconnect ECM/PCM connector B (44P).

15. Check for continuity between ECM/PCM connector terminal B4 and body ground.

Is there continuity?
YES - Repair short in the wire between the ECM/PCM (B4) and secondary HO2S (Sensor 2), then go to step 22.

NO - Go to step 28.






16. Measure the voltage between secondary HO2S (Sensor 2) 4P connector terminal No. 3 and body ground.

Is there battery voltage?
YES - Go to step 17.

NO - Repair open in the wire between secondary HO2S (Sensor 2) and the No. 3 ALTERNATOR (10 A) fuse, then go to step 22.






17. Turn the ignition switch to LOCK (0).

18. Jump the SCS line with the HDS.

19. Disconnect ECM/PCM connector B (44P).

20. Check for continuity between secondary HO2S (Sensor 2) 4P connector terminal No. 4 and ECM/PCM connector terminal B4.

Is there continuity?
YES - Go to step 28.

NO - Repair open in the wire between the ECM/PCM (B4) and secondary HO2S (Sensor 2), then go to step 22.






21. Replace secondary HO2S (Sensor 2). Secondary HO2S Replacement

22. Reconnect all connectors.

23. Turn the ignition switch to ON (II).

24. Reset the ECM/PCM with the HDS.

25. Do the ECM/PCM idle learn procedure. ECM/PCM Idle Learn Procedure

26. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0141 indicated?
YES - Check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the ECM/PCM, then go to step 1.

NO - Go to step 27.


27. Monitor the OBD STATUS for DTC P0141 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?
YES - Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 26, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the ECM/PCM, then go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.


28. Reconnect all connectors.

29. Update the ECM/PCM if it does not have the latest software, ECM/PCM Update or substitute a known-good ECM/PCM. Reading and Clearing Diagnostic Trouble Codes

30. Start the engine, and let it idle.

31. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0141 indicated?
YES - Check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the ECM/PCM. If the ECM/PCM was update, substitute a known-good ECM/PCM, Reading and Clearing Diagnostic Trouble Codes then go to step 30. If the ECM/PCM was substitute, go to step 1.

NO - Go to step 32.


32. Monitor the OBD STATUS for DTC P0141 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?
YES - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM. Service and Repair If any other Pending or Confirmed DTCs were indicated in step 31, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM, Reading and Clearing Diagnostic Trouble Codes then go to step 30. If the ECM/PCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.