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 A/F sensor relay (LAF), and the ECM.
5. Turn the ignition switch to LOCK (0).
6. Check these fuses:
- No. 15 LAF ('06-07 models: 20 A , '08-09 models: 15 A) fuse in the under-dash fuse/relay box.
- No. 10 IGP (LAF) (7.5 A) fuse in the under-dash fuse/relay box.
- No. 59 DBW (20 A) fuse in the under-hood fuse/relay box.
Are any of the above fuses blown?
YES - Repair short in the wire between 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 A/F sensor (Sensor 1) 4P connector.
8. At the A/F sensor side, measure the resistance between A/F sensor (Sensor 1) 4P connector terminals No. 3 and No. 4.
Is there 2.1-2.9 Ohms at room temperature?
YES - Go to step 9.
NO - Go to step 22.
9. At the A/F sensor side, check for continuity between A/F sensor (Sensor 1) 4P connector terminal No. 2 and A/F sensor (Sensor 1) 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 ECM connector A (31P).
12. Check for continuity between ECM connector terminal A10 and body ground.
Is there continuity?
YES - Repair short in the wire between the ECM (A10) and the A/F sensor (Sensor 1), then go to step 23.
NO - Go to step 13.
13. Connect A/F sensor (Sensor 1) 4P connector terminal No. 4 to body ground with a jumper wire.
14. Check for continuity between ECM connector terminal A10 and body ground.
Is there continuity?
YES - Go to step 15.
NO - Repair open in the wire between the ECM (A10) and the A/F sensor (Sensor 1), then go to step 23.
15. Remove the A/F sensor relay (LAF) (A).
16. Connect A/F sensor (Sensor 1) 4P connector terminal No. 3 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 A/F sensor (Sensor 1) and the A/F sensor relay (LAF), then go to step 23.
18. Disconnect ECM connector E (31P).
19. Check for continuity between ECM connector terminal E8 and body ground.
Is there continuity?
YES - Repair short in the wire between the ECM (E8) and the A/F sensor relay (LAF), then go to step 23.
NO - Go to step 20.
20. Check for continuity between ECM connector terminal E8 and A/F sensor relay (LAF) 4P connector terminal No. 3.
Is there continuity?
YES - Go to step 21.
NO - Repair open in the wire between the ECM (E8) and the A/F sensor relay (LAF), then go to step 23.
21. Check the A/F sensor relay (LAF). Testing and Inspection
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 A/F sensor (Sensor 1). A/F Sensor Replacement
23. Reconnect all connectors.
24. Turn the ignition switch to ON (II).
25. Reset the ECM with the HDS.
26. Do the ECM idle learn procedure. ECM Idle Learn Procedure
27. 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) and the ECM, then go to step 1.
NO - Go to step 28.
28. 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 27, 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) and the ECM, 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 ECM if it does not have the latest software, ECM Update or substitute a known-good ECM. Initial Inspection and Diagnostic Overview
31. Start the engine, and let it idle.
32. 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 A/F sensor relay (LAF), and the ECM. If the ECM was updated, substitute a known-good ECM, Initial Inspection and Diagnostic Overview then go to step 31. If the ECM was substituted, go to step 1.
NO - Go to step 33.
33. 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 32, 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 A/F sensor relay (LAF), and the ECM. If the ECM was updated, substitute a known-good ECM, Initial Inspection and Diagnostic Overview then go to step 31. If the ECM was substituted, go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.