DTC Troubleshooting

DTC Troubleshooting: P1157

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

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, 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.


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

6. Jump the SCS line with the HDS.

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

8. Disconnect ECM 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 ECM 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. 2 to body ground with a jumper wire.






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

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

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






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

15. Reconnect all connectors.

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

17. Reset the ECM with the HDS.

18. Do the ECM idle learn procedure. ECM 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 ECM, then go to step 1. If the connections and the terminals 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 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.


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

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 ECM was updated, substitute a known-good ECM, Initial Inspection and Diagnostic Overview then go to step 22. If the ECM 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 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 23, go to the indicated DTC's troubleshooting.

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