DTC Troubleshooting

DTC Troubleshooting: P0135

DTC P0135: A/F Sensor (Sensor 1) Heater Circuit Malfunction

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information. Initial Inspection and Diagnostic Overview

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

2. Clear the DTC with the HDS.

3. Start the engine. Hold the engine speed at 3,000 rpm without load (in neutral) until the radiator fan comes on, then let it idle.

4. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0135 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 A/F sensor (Sensor 1), the PGM-FI subrelay, and the ECM.


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

6. Check the No. 11 FI SUB (15 A) fuse in the under-hood fuse/relay box.

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

NO - Go to step 20.


7. Test the PGM-FI subrelay (E) in the under-hood fuse/relay box. Power Relay Test

Is the PGM-FI subrelay OK?
YES - Go to step 8.

NO - Replace the PGM-FI subrelay, then go to step 24.






8. Disconnect the A/F sensor (Sensor 1) 4P connector.

9. At the sensor side, measure the resistance between A/F sensor (Sensor 1) 4P connector terminals No. 3 and No. 4.

Is there 2.0-2.7 Ohms at room temperature?
YES - Go to step 10.

NO - Go to step 24.






10. At the sensor side, check for continuity between A/F sensor (Sensor 1) 4P connector terminals No. 1 and No. 3, and between terminals No. 1 and No. 4 individually.

Is there continuity?
YES - Go to step 24.

NO - Go to step 11.






11. Jump the SCS line with the HDS.

12. Disconnect ECM connector C (44P).

13. Connect A/F sensor (Sensor 1) 4P connector terminal No. 3 to body ground with a jumper wire.






14. Check for continuity between ECM connector terminal C9 and body ground.

Is there continuity?
YES - Go to step 15.

NO - Repair open in the wire between the ECM (C9) and the A/F sensor (Sensor 1), then go to step 25.






15. Remove the PGM-FI subrelay (E) from the under-hood fuse/relay box.






16. Connect A/F sensor (Sensor 1) 4P connector terminal No. 4 to body ground with a jumper wire.






17. Check for continuity between PGM-FI subrelay 4P connector terminal No. 2 and body ground.

Is there continuity?
YES - Go to step 18.

NO - Repair open in the wire between the A/F sensor (Sensor 1) and the PGM-FI subrelay, then go to step 25.






18. Disconnect ECM connector A (44P).

19. Check for continuity between PGM-FI subrelay 4P connector terminal No. 3 and ECM connector terminal A21.

Is there continuity?
YES - Go to step 31.

NO - Repair open in the wire between the ECM (A21) and the PGM-FI subrelay, then go to step 25.






20. Remove the PGM-FI subrelay (E) from the under-hood fuse/relay box.

21. Disconnect the A/F sensor (Sensor 1) 4P connector.

22. Disconnect the EVAP canister vent shut valve 2P connector.






23. Check for continuity between A/F sensor (Sensor 1) 4P connector terminal No. 4 and body ground.

Is there continuity?
YES - Repair short in the wire between the PGM-FI subrelay, the EVAP canister vent shut valve, and the A/F sensor (Sensor 1). Also replace the No. 11 FI SUB (15 A) fuse, then go to step 25.

NO - Replace the under-hood fuse/relay box, Under-Hood Fuse/Relay Box Removal and Installation then go to step 25.






24. Replace the A/F sensor (Sensor 1). A/F Sensor Replacement

25. Reconnect all connectors.

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

27. Reset the ECM with the HDS.

28. Do the ECM idle learn procedure. ECM Idle Learn Procedure

29. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0135 indicated?
YES - Check for poor connections or loose terminals at the A/F sensor (Sensor 1), the PGM-FI subrelay, and the ECM, then go to step 1.

NO - Go to step 30.


30. Monitor the OBD STATUS for DTC P0135 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 29, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the A/F sensor (Sensor 1), the PGM-FI subrelay, and the ECM, then go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.


31. Reconnect all connectors.

32. Update the ECM if it does not have the latest software, ECM Update or substitute a known-good ECM. Initial Inspection and Diagnostic Overview

33. Start the engine, and let it idle.

34. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0135 indicated?
YES - Check for poor connections or loose terminals at the A/F sensor (Sensor 1), the PGM-FI subrelay, and the ECM. If the ECM was updated, substitute a known-good ECM, Initial Inspection and Diagnostic Overview then go to step 33. If the ECM was substituted, go to step 1.

NO - Go to step 35.


35. Monitor the OBD STATUS for DTC P0135 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?
YES - If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. Service and Repair If any other Temporary DTCs or DTCs were indicated in step 34, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the A/F sensor (Sensor 1), the PGM-FI subrelay, and the ECM. If the ECM was updated, substitute a known-good ECM, Initial Inspection and Diagnostic Overview then go to step 33. If the ECM was substituted, go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.