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 PGM-FI subrelay (LAF), the driver's under-dash fuse/relay box, and the PCM.
5. Turn the ignition switch OFF.
6. Check these fuses:
- No. 19 OPTION 1 (30 A) fuse in the under-hood fuse/relay box.
- No. 4 LAF (A/F SENSOR) (15 A) fuse in the driver's under-dash fuse/relay box.
- No. 23 IGP (7. 5 A) fuse in the under-dash fuse/relay box.
Are any of the fuses blown?
YES - Repair short in the wire between the A/F sensors, the PGM-FI subrelay (LAF), and the fuse, then go to step 22.
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 - 6.60 ohms at room temperature?
YES - Go to step 9.
NO - Go to step 21.
9. 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. Jump the SCS line with the HDS.
11. Disconnect PCM connector C (49P).
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 21.
NO - Go to step 13.
13. Check for continuity between PCM secondary HO2S (Sensor 2) 4P connector terminal No. 3 and PCM connector terminal C5 (C7)*.
Is there continuity?
YES - Go to step 14.
NO - Repair open in the wire between the PCM (C5 (C7)*) and the secondary HO2S (Sensor 2), then go to step 22.
14. Remove the PGM-FI subrelay (LAF) (A).
15. Connect secondary HO2S (Sensor 2) 4P connector terminal No. 4 to body ground with a jumper wire.
16. Check for continuity between PGM-FI subrelay (LAF) 4P connector terminal No. 2 and body ground.
Is there continuity?
YES - Go to step 17.
NO - Repair open in the wire between the secondary HO2S (Sensor 2) and the PGM-FI subrelay (LAF), then go to step 22.
17. Disconnect PCM connector A (49P).
18. Connect PGM-FI subrelay (LAF) 4P connector terminal No. 3 to body ground with a jumper wire.
19. Check for continuity between PCM connector terminal A40 and body ground.
Is there continuity?
YES - Go to step 20.
NO - Repair open in the wire between the PCM (A21) and the PGM-FI subrelay (LAF), then go to step 22.
20. Test the PGM-FI subrelay (LAF).
Is the PGM-FI subrelay (LAF) OK?
YES - Go to step 29.
NO - Replace the PGM-FI subrelay (LAF), then go to step 23.
21. Replace the secondary HO2S (Sensor 2).
22. Reconnect all connectors.
23. Turn the ignition switch ON (II).
24. Reset the PCM with the HDS.
25. Do the PCM idle learn procedure.
26. 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 PGM-FI subrelay (LAF), and the PCM, then go to step 1.
NO - Go to step 27.
27. 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 26, 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 PGM-FI subrelay (LAF), and the 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 PCM if it does not have the latest software, or substitute a known-good PCM.
30. 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 PGM-FI subrelay (LAF), and the PCM. If the PCM was updated, substitute a known-good PCM, then recheck. If the PCM was substituted, go to step 1.
NO - Go to step 31.
31. 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 30, 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 PGM-FI subrelay (LAF), and the PCM. If the PCM was updated, substitute a known-good PCM, then recheck. If the PCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.