P0135

DTC P0135: A/F Sensor (Sensor 1) Heater Circuit Malfunction (2003 AT-PZEV (SULEV) and 2004-2005 models)

NOTE: Information marked with an asterisk (*) applies to 2003 ULEV model.

1. Reset the ECM with the HDS.
2. Start the engine.
3. check for Temporary DTCs or DTCs with the HDS.

Is DTC P0135 (P1166)* indicated?

YES - Go to step 4.

NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the A/F sensor relay, the A/F sensor (Sensor 1), and the ECM.




4. Measure voltage between ECM connector terminals A1 and A24, 30 seconds after the ignition switch is turned ON (II).

Is there battery voltage?

YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.

NO - Go to step 5.




5. Measure voltage between ECM connector terminals A22 and A24.

Is there battery voltage?

YES - Go to step 6.

NO - Go to step 11.

6. Turn the ignition switch OFF.
7. Wait for 1 minute. If the radiator fan is running, wait for 1 minute after it stops.
8. Disconnect ECM connector A (31P).
9. Turn the ignition switch ON (II).




10. Connect ECM connector terminal E8 to body ground with a jumper wire, then measure voltage between ECM connector terminals A1 and A24.

Is there battery voltage?

YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.

NO - Repair open or short in the wire between A/F sensor (Sensor 1) and the ECM (A1).

11. Turn the ignition switch OFF.
12. Wait for 1 minute. If the radiator fan is running, wait for 1 minute after it stops.
13. Disconnect ECM connector A (31P) and the A/F sensor (Sensor 1) 4P connector.




14. Check for continuity between A/F sensor (Sensor 1) 4P connector terminal No.3 and body ground.

Is there continuity?

YES - Repair short in the wire between the A/F sensor relay, A/F sensor (Sensor 1), and the ECM (A22).

NO - Go to step 15.

15. Reconnect ECM connector A (31P).
16. Turn the ignition switch ON (II).




17. Measure voltage between ECM connector terminals E8 and A24.

Is there battery voltage?

YES - Repair open in the wire between the ECM (A22) and the A/F sensor (Sensor 1) or A/F sensor relay.

NO - Go to step 18.

18. Check the following fuses:

- No.14 OPTION (40 A) fuse in the under-hood fuse/relay box.
- No.4 FI-ECU (10 A) fuse in the under-dash fuse/relay box.
- No.2 LAF (A/F) HEATER (20 A) in the under-dash fuse/relay box.

Are any of the fuses blown?

YES - Repair short in the wire between the A/F sensor relay and the fuses.

NO - Go to step 19.

19. Check for continuity in the wires between the A/F sensor relay and the fuses.

Is there continuity?

YES - The wires are OK, replace the A/F sensor relay.

NO - Repair open in the wire between the A/F sensor relay and the fuses.