( TL19E30A20300000000HAAT11 )

Idle speed fluctuates (MIL works OK, no DTCs set)

Diagnostic procedure

1. Do the ECM/PCM idle learn procedure.
2. Check the fuel pressure.
3. Except KN model: Test the injectors.
4. Troubleshoot the alternator FR signal circuit.
5. Inspect the PCV valve.
6. Test the throttle body.
7. Troubleshoot the A/C signal circuit.
8. Troubleshoot the VTEC system oil pressure.

Also check for

- Fuel contamination
- Intake vacuum leaks