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. Reading and Clearing Diagnostic Trouble Codes

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 Pending or Confirmed 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 to LOCK (0).

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). A/F Sensor Replacement

12. Reconnect all connectors.

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

14. Reset the ECM/PCM with the HDS.

15. Do the ECM/PCM idle learn procedure. ECM/PCM Idle Learn Procedure

16. Check for Pending or Confirmed 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 connections and the terminals 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 Pending or Confirmed 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, ECM/PCM Update or substitute a known-good ECM/PCM. Reading and Clearing Diagnostic Trouble Codes

19. Start the engine, and let it idle.

20. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P1157 indicated?
YES - If the ECM/PCM was updated, substitute a known-good ECM/PCM, Reading and Clearing Diagnostic Trouble Codes 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. Service and Repair If any other Pending or Confirmed DTCs were indicated in step 20, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, go to step 1. If the ECM/PCM was updated, substitute a known-good ECM/PCM, Reading and Clearing Diagnostic Trouble Codes 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.