P1157

DTC P1157: A/F Sensor (Sensor 1) Range/Performance Problem

1. Reset the ECM/PCM.
2. Start the engine.

Is DTC P1157 indicated?

YES - Go to step 3.

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/PCM.

3. Turn the ignition switch OFF.
4. Disconnect the A/F sensor (Sensor 1) 4P connector and ECM/PCM connector A (31P).




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




6. Check for continuity between ECM/PCM connector terminals A6 and A16.

Is there continuity?

YES - Go to step 9.

NO - Go to step 7.




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




8. Check for continuity between ECM/PCM 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/PCM (A16).

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

9. Substitute a known-good A/F sensor (Sensor 1) and recheck.

Is DTC P1157 indicated?

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

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