P1157

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

1. Reset the ECM with the HDS.
2. Start the engine.
3. check for Temporary DTCs or DTCs with the HDS.

Is DTC P1157 indicated?

YES - Go to step 4.

NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the A/F sensor (Sensor 1) and at the ECM.

4. Turn the ignition switch OFF.
5. Wait for 1 minute. If the radiator fan is running, wait for 1 minute after it stops.
6. Disconnect the A/F sensor (Sensor 1) 4P connector and ECM connector A (31P).




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




8. Check for continuity between ECM connector terminals A6 and A16.

Is there continuity?

YES - Go to step 11.

NO - Go to step 9.




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




10. Check for continuity between ECM connector terminals A6 and body ground.

Is there continuity?

YES - Repair open in the wire between the A/F sensor (Sensor 1) and the ECM (A16).

NO - Repair open in the wire between the A/F sensor (Sensor 1) and the ECM (A6).

11. Substitute a known-good A/F sensor (Sensor 1) and recheck.
12. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P1157 indicated?

YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.

NO - Replace the A/F sensor (Sensor 1).