P0657
DTC P0657: A/F Sensor Relay Circuit Malfunction1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Check for Temporary DTCs or DTCs with the HDS.
Are any Temporary DTCs or DTCs indicated?
YES - Go to step 4.
NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the PCM, and A/F sensor relay, and fuse No.9 LAFHT (15 A) in the under-hood subfuse box.
4. Turn the ignition switch OFF.
5. Jump the SCS line with the HDS.
6. Disconnect PCM connector B (56P).
7. Remove the A/F sensor relay (A).
8. Connect the A/F sensor relay 4P connector No.3 terminal and body ground with a jumper wire.
9. Check for continuity between PCM connector terminal B10 and body ground.
Is there continuity?
YES - Go to step 10.
NO - Repair open in the wire between the PCM (B10) and A/F sensor relay, then go to step 12.
10. Check for continuity between PCM connector terminal B10 and body ground.
Is there continuity?
YES - Repair short in the wire between the PCM (B10) and A/F sensor relay, then go to step 12.
NO - Go to step 11.
11. Measure voltage between the A/F sensor relay 4P connector terminal No.4 and body ground.
Is there battery voltage?
YES - Go to step 17.
NO - Repair open in the wire between the A/F sensor relay and the No.9 LAFHT (15 A) fuse in the under-hood subfuse box. If the No.9 LAFHT (15 A) fuse is blown, repair the cause, then go to step 12.
12. Install the A/F sensor relay, and reconnect PCM connector B (56P).
13. Turn the ignition switch ON (II).
14. Reset the PCM with the HDS.
15. Do the PCM idle learn procedure.
16. Check for Temporary DTCs or DTCs with the HDS.
Are any Temporary DTCs or DTCs indicated?
YES - If DTC P0657 is indicated, check for poor connections or loose terminals at A/F sensor relay and PCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO - Troubleshooting is complete.
17. Test the A/F sensor relay.
Is the relay OK?
YES - Go to step 22.
NO - Replace the A/F sensor relay, then go to step 18.
18. Turn the ignition switch ON (II).
19. Reset the PCM with the HDS.
20. Do the PCM idle learn procedure.
21. Check for Temporary DTCs or DTCs with the HDS.
Are any Temporary DTCs or DTCs indicated?
YES - If DTC P0657 is indicated, check for poor connections or loose terminals at A/F sensor relay and PCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO - Troubleshooting is complete.
22. Update the PCM if it does not have the latest software, or substitute a known-good PCM.
23. Turn the ignition switch ON (II).
24. Check for Temporary DTCs or DTCs with the HDS.
Are any Temporary DTCs or DTCs indicated?
YES - If DTC P0657 is indicated, check for poor connections or loose terminals at A/F sensor relay and the PCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM.