P0519
Idle Air Control System Performance
The idle air control system is electrically intact, but the actual idle airflow does not match the commanded value - typical for a sticky valve, intake leak, or carbon build-up around the throttle bore.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: easy
Symptoms
- Check engine light on
- Idle speed too high, too low, or unstable
- Possible stalling at idle or after cold start
Common causes
Ordered by how often each turns out to be the cause.
- IAC valve sticking due to carbonCommon
- Intake leak disturbs idle meteringPossible
Parts involved
- Idle Air Control Valve
- Intake Manifold
- Throttle Body
P0519 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.