P1157

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 ECM/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 ECM/PCM connector C (44P).




9. Check for continuity between A/F sensor (Sensor 1) 4P connector terminal No.2 and ECM/PCM connector terminal C29.

Is there continuity?

YES - Go to step 10.

NO - Repair open in the wire between the ECM/PCM (C29) and the A/F sensor (Sensor 1), then go to step 12.




10. Check for continuity between A/F sensor (Sensor 1) 4P connector terminal No.1 and ECM/PCM connector terminal C30.

Is there continuity?

YES - Go to step 11.

NO - Repair open in the wire between the ECM/PCM (C30) and the A/F sensor (Sensor 1), then go to step 12.

11. Replace the A/F sensor (Sensor 1).
12. Reconnect all connectors.
13. Turn the ignition switch ON (II).
14. Reset the ECM/PCM with the HDS.
15. Do the ECM/PCM idle learn procedure.
16. 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 ECM/PCM, then go to step 1. If the connector and terminal fits are OK, go to step 18.

NO - Go to step 17.

17. 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 16, 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/PCM, then go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.

18. Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM.
19. Start the engine, and let it idle.
20. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P1157 indicated?

YES - If the ECM/PCM was updated, substitute a known-good ECM/PCM, then go to step 19. If the ECM/PCM was substituted, go to step 1.

NO - Go to step 21.

21. Monitor the OBD STATUS for DTC P1157 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?

YES - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM. If any other Temporary DTCs or DTCs were indicated in step 20, go to the indicated DTCs troubleshooting.

NO - If the screen indicates FAILED, go to step 1. If the ECM/PCM was updated, substitute a known-good ECM/PCM, then go to step 19. If the ECM/PCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.