Cause
Faulty idle air control valve
The valve metering air around a closed throttle on engines that have one. A vacuum leak produces exactly the same complaint, so an unstable or stalling idle is not evidence for this valve until the intake has been checked — which is why the valve gets replaced so often without fixing anything.
Typically a moderate job.
Codes this can cause (8)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0505 Idle Air Control System Likely for this code Moderate
- P0508 Idle Air Control System Circuit Low Likely for this code Low
- P0509 Idle Air Control System Circuit High Likely for this code Low
- P0511 Idle Air Control Circuit Likely for this code Low
- P0518 Idle Air Control Circuit Intermittent Likely for this code Low
- P0506 Idle Air Control System RPM Lower Than Expected Moderate
- P0507 Idle Air Control System RPM Higher Than Expected Moderate
- P0519 Idle Air Control System Performance Moderate
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