DTC P0511: IAC Valve 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.
Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0511 indicated?
1. YES - Go to step 4.
2. NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the IAC valve and the ECM/PCM.
Turn the ignition switch OFF.
Disconnect the IAC valve 3P connector.
Turn the ignition switch ON (II).
Measure voltage between IAC valve 3P connector terminal No. 2 and body ground.

Fig 1: Measuring Voltage Between IAC Valve 3P Connector Terminal And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Go to step 8.
2. NO - Repair open in the wire between the IAC valve and PGM-FI main relay 1 (FI MAIN), then go to step 21.
Turn the ignition switch OFF.
Check for continuity between body ground and IAC valve 3P connector terminal No. 1.

Fig 2: Checking Continuity Between Body Ground And IAC Valve 3P Connector Terminal
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Go to step 10.
2. NO - Repair open in the wire between the IAC valve and G101, then go to step 21.
Turn the ignition switch OFF.
Jump the SCS line with the HDS.
Disconnect ECM/PCM connector A (31P).
Check for continuity between ECM/PCM connector terminal A12 and body ground.

Fig 3: Checking Continuity Between ECM/PCM Connector Terminal A12 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Repair short in the wire between the ECM/PCM (A12) and the IAC valve, then go to step 21.
2. NO - Go to step 14.
Connect IAC valve 3P connector terminal No. 3 to body ground with a jumper wire.

Fig 4: Connecting IAC Valve 3P Connector Terminal To Body Ground With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between ECM/PCM connector terminal A12 and body ground.

Fig 5: Checking Continuity Between ECM/PCM Connector Terminal A12 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Go to step 16.
2. NO - Repair open in the wire between the ECM/PCM (A12) and the IAC valve, then go to step 21.
Reconnect the IAC valve 3P connector.
Turn the ignition switch ON (II).
Measure voltage between ECM/PCM connector terminal A12 and body ground.

Fig 6: Measuring Voltage Between ECM/PCM Connector Terminal A12 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Go to step 26.
2. NO - Go to step 19.
Turn the ignition switch OFF.
Replace the IAC valve (see THROTTLE BODY DISASSEMBLY/REASSEMBLY ).
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.
Are any Temporary DTCs or DTCs indicated?
1. YES - If DTC P0511 is indicated, check for poor connections or loose terminals at the IAC valve and the ECM/PCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
2. NO - Go to step 25.
Monitor the OBD STATUS for DTC P0511 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
1. YES - Troubleshooting is complete.
2. NO - If the screen indicates FAILED, go to step 1 and recheck. If the screen indicates NOT COMPLETED, go to 23 and recheck.
Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM (see ECM/PCM UPDATING AND SUBSTITUTION FOR TESTING ).
Check for Temporary DTCs or DTCs with the HDS.
Are any Temporary DTCs or DTCs indicated?
1. YES - If DTC P0511 is indicated, check for poor connections or loose terminals at the IAC valve and the ECM/PCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
2. NO - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM (see ECM/PCM REPLACEMENT ).