DTC Troubleshooting
DTC P0141: Rear Secondary HO2S (Bank 1, Sensor 2) Heater Circuit MalfunctionDTC P0161: Front Secondary HO2S (Bank 2, Sensor 2) Heater Circuit Malfunction
NOTE:
- Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.
- Information marked with an asterisk (*) applies to the front bank (Bank 2).
1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Start the engine.
4. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0141 and/or P0161* indicated?
YES - Go to step 5.
NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the secondary HO2S (Sensor 2), the A/F sensor relay (LAF), and the PCM.
5. Turn the ignition switch OFF.
6. Check these fuses:
- No. 9 LAF (A/F SENSOR) (15 A) fuse in the auxiliary under-hood fuse/relay box
- 7.5 A fuse in the auxiliary under-dash fuse holder
Are any of the fuses blown?
YES - Repair short in the wire between the secondary HO2S (Sensor 2), the A/F sensor relay (LAF), and the fuse(s). Also replace the blown fuse(s), then go to step 23.
NO - Go to step 7.
7. Disconnect the secondary HO2S (Sensor 2) 4P connector.
8. At the secondary HO2S (Sensor 2) side, measure 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 22.
9. At the secondary HO2S (Sensor 2) 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 22.
NO - Go to step 10.
10. Jump the SCS line with the HDS.
11. Disconnect PCM connector C (44P).
12. Check for continuity between PCM connector terminal C5 (C7)* and body ground.
Is there continuity?
YES - Repair short in the wire between the PCM (C5 (C7)*) and the secondary HO2S (Sensor 2), then go to step 23.
NO - Go to step 13.
13. Connect secondary HO2S (Sensor 2) 4P connector terminal No. 3 to body ground with a jumper wire.
14. Check for continuity between PCM connector terminal C5 (C7)* and body ground.
Is there continuity?
YES - Go to step 15.
NO - Repair open in the wire between the PCM (C5 (C7)*) and the secondary HO2S (Sensor 2), then go to step 23.
15. Remove the A/F sensor relay (LAF) (A).
16. Connect secondary HO2S (Sensor 2) 4P connector terminal No. 4 to body ground with a jumper wire.
17. Check for continuity between A/F sensor relay (LAF) 4P connector terminal No. 2 and body ground.
Is there continuity?
YES - Go to step 18.
NO - Repair open in the wire between the secondary HO2S (Sensor 2) and the A/F sensor relay (LAF), then go to step 23.
18. Disconnect PCM connector A (44P).
19. Connect A/F sensor relay (LAF) 4P connector terminal No. 3 to body ground with a jumper wire.
20. Check for continuity between PCM connector terminal A21 and body ground.
Is there continuity?
YES - Go to step 21.
NO - Repair open in the wire between the PCM (A21) and the A/F sensor relay (LAF), then go to step 23.
21. Test the A/F sensor relay (LAF). Is the A/F sensor relay (LAF) OK?
YES - Go to step 29.
NO - Replace the A/F sensor relay (LAF), then go to step 23.
22. Replace the secondary HO2S (Sensor 2).
23. Reconnect all connectors.
24. Turn the ignition switch ON (II).
25. Reset the PCM with the HDS.
26. Do the PCM idle learn procedure.
27. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0141 and/or P0161* indicated?
YES - Check for poor connections or loose terminals at the secondary HO2S (Sensor 2), the A/F sensor relay (LAF), and the PCM, then go to step 1.
NO - Go to step 28.
28. Monitor the OBD STATUS for DTC P0141 and/or P0161* in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES - Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 27, go to the indicated DTCs troubleshooting.
NO - If the screen indicates FAILED, check for poor connections or loose terminals at the secondary HO2S (Sensor 2), the A/F sensor relay (LAF), and the PCM, then go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.
29. Reconnect all connectors.
30. Update the PCM if it does not have the latest software, or substitute a known-good PCM.
31. Start the engine, and let it idle.
32. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0141 and/or P0161* indicated?
YES - Check for poor connections or loose terminals at the secondary HO2S (Sensor 2), the A/F sensor relay (LAF), and the PCM, then go to step 1. If the PCM was updated, substitute a known-good PCM, then go to step 31. If the PCM was substituted, go to step 1.
NO - Go to step 33.
33. Monitor the OBD STATUS for DTC P0141 and/or P0161* in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM. If any other Temporary DTCs or DTCs were indicated in step 32, go to the indicated DTCs troubleshooting.
NO - If the screen indicates FAILED, check for poor connections or loose terminals at the secondary HO2S (Sensor 2), the A/F sensor relay (LAF), and the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 31. If the PCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.