P0511
Idle Air Control Circuit
A general circuit fault is detected on the idle air control valve - open or short on supply, signal or ground. The ECU loses control of idle bypass airflow.
- Check engine light: Yes
- Emissions related: No
- 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.
- Open in valve or wiringCommon
Parts involved
- Idle Air Control Valve
- IAC Wiring
P0511 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.