DTC Troubleshooting

Control System DTCs

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 How To Troubleshoot The Fuel And Emissions Systems.

1. Problem verification:

Problem verification
-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- The failure is duplicated. Go to step 2.
-NO- Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the A/F sensor (Sensor 1), the PGM-FI subrelay, and the ECM.

2. Open wire check (AFS+ line):

Open wire check (AFS+ line)
-1. Turn the ignition switch to LOCK (0).

-2. Jump the SCS line with the HDS.

-3. Disconnect the following connectors.





-4. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The AFS+ wire is OK. Go to step 3.
-NO- Repair an open in the AFS+ wire between the ECM (C39) and the A/F sensor (Sensor 1), then do the repair verification.

3. Open wire check (AFS- line):

Open wire check (AFS- line)
-1. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The AFS- wire is OK. Go to step 4.
-NO- Repair an open in the AFS- wire between the ECM (C40) and the A/F sensor (Sensor 1), then do the repair verification.

4. A/F sensor (Sensor 1) check (substitution):

A/F sensor (Sensor 1) check (substitution)
-1. Substitute a known-good A/F sensor (Sensor 1).

-2. Reconnect all connectors.

-3. Turn the ignition switch to ON (II).

-4. Reset the ECM with the HDS How To Troubleshoot The Fuel And Emissions Systems.

-5. Do the ECM idle learn procedure ECM/PCM Idle Learn Procedure.

-6. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P1157 indicated?
-YES- The A/F sensor (Sensor 1) is OK. Update the ECM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM Service and Repair, then do the repair verification.
-NO- Replace the original A/F sensor (Sensor 1) A/F Sensor Removal and Installation, then do the repair verification.

Repair verification:

-1. Turn the ignition switch to LOCK (0).

-2. Reconnect all connectors.

-3. Turn the ignition switch to ON (II).

-4. Reset the ECM with the HDS How To Troubleshoot The Fuel And Emissions Systems.

-5. Do the ECM idle learn procedure ECM/PCM Idle Learn Procedure.

-6. 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. If the ECM was updated, substitute a known-good ECM Service and Repair, then recheck. If the ECM was substituted, go to step 1.
-NO- Troubleshooting is complete. If the ECM was substituted, replace the original ECM Service and Repair. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.