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

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).

Turn the ignition switch ON (II).
Clear the DTC with the HDS.
Start the engine, and wait 1 minute.
Check for Temporary DTCs or 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.
Turn the ignition switch OFF.
Jump the SCS line with the HDS.
Disconnect the A/F sensor (Sensor 1) 4P connector.
Disconnect ECM/PCM connector C (44P).
Connect A/F sensor (Sensor 1) 4P connector terminals No. 1 and No. 2 with a jumper wire.

Fig 1: Connecting A/F Sensor (Sensor 1) 4P Connector Terminals 1 And 2 With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between ECM/PCM connector terminals C29 and C30.

Fig 2: Checking Continuity Between ECM/PCM Connector Terminals C29 And C30
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 14.

NO -Go to step 11.
Remove the jumper wire from the A/F sensor (Sensor 1) 4P connector.
Connect A/F sensor (Sensor 1) 4P connector terminal No. 2 to body ground with a jumper wire.

Fig 3: Connecting A/F Sensor (Sensor 1) 4P Connector Terminal 2 To Body Ground With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between ECM/PCM connector terminal C29 and body ground.

Fig 4: Checking Continuity Between ECM/PCM Connector Terminal C29 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair open in the wire between the ECM/PCM (C30) and the A/F sensor (Sensor 1), then go to step 15.

NO -Repair open in the wire between the ECM/PCM (C29) and the A/F sensor (Sensor 1), then go to step 15.
Replace the A/F sensor (Sensor 1) (see A/F SENSOR REPLACEMENT ).
Reconnect all connectors.
Turn the ignition switch ON (II).
Reset the ECM/PCM with the HDS.
Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
Check for Temporary DTCs or 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 connector and terminal fits are OK, go to step 21.

NO -Go to step 20.
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 Temporary DTCs or DTCs were indicated in step 19, 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.
Update the ECM/PCM if it does not have the latest software (see UPDATING THE ECM/PCM ), or substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ).
Start the engine, and let it idle.
Check for Temporary DTCs or DTCs with the HDS.
Is DTC P1157 indicated?

YES -If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then go to step 22. If the ECM/PCM was substituted, go to step 1.

NO -Go to step 24.
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 (see ECM/PCM REPLACEMENT ). If any other Temporary DTCs or DTCs were indicated in step 23, 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 (see SUBSTITUTING THE ECM/PCM ), then go to step 22. If the ECM/PCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.