DTC Troubleshooting

DTC P1157: A/F Sensor (Sensor 1) AFS Circuit Malfunction

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

1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Start the engine, and wait 1 minute.
4. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P1157 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) and the PCM.

5. Turn the ignition switch OFF.
6. Jump the SCS line with the HDS.
7. Disconnect the A/F sensor (Sensor 1) 4P connector.
8. Disconnect PCM connector C (44P).




9. Connect A/F sensor (Sensor 1) 4P connector terminals No. 1 and No. 2 with a jumper wire.




10. Check for continuity between PCM connector terminals C29 and C30.

Is there continuity?

YES - Go to step 14.

NO - Go to step 11.

11. Remove the jumper wire from the A/F sensor (Sensor 1) 4P connector.




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




13. Check for continuity between PCM connector terminal C29 and body ground.

Is there continuity?

YES - Repair open in the wire between the PCM (C30) and the A/F sensor (Sensor 1), then go to step 15.

NO - Repair open in the wire between the PCM (C29) and the A/F sensor (Sensor 1), then go to step 15.

14. Replace the A/F sensor (Sensor 1).
15. Reconnect all connectors.
16. Turn the ignition switch ON (II).
17. Reset the PCM with the HDS.
18. Do the PCM idle learn procedure.
19. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P1157 indicated?

YES - Check for poor connections or loose terminals at the A/F sensor (Sensor 1) and the PCM, then go to step 1. If the connector and terminal fits are OK, go to step 21.

NO - Go to step 20.

20. Monitor the OBD STATUS for DTC P1157 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 19, go to the indicated DTCs troubleshooting.

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

21. Update the PCM if it does not have the latest software, or substitute a known-good PCM.
22. Start the engine, and let it idle.
23. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P1157 indicated?

YES - If the PCM was updated, substitute a known-good PCM, then go to step 22. If the PCM was substituted, go to step 1.

NO - Go to step 24.

24. Monitor the OBD STATUS for DTC P1157 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 23, go to the indicated DTCs troubleshooting.

NO - If the screen indicates FAILED, go to step 1. If the PCM was updated, substitute a known-good PCM, then go to step 22. If the PCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.