P050A
Cold Start Idle Control System Performance
During the cold-start phase the ECU runs an elevated idle speed and a richer mixture to bring the catalyst above light-off temperature quickly. The cold-start idle does not behave as commanded - speed sags, hunts, or fails to come up. Possible causes are intake leaks active when cold, an IAC valve sticking, or implausible coolant temperature.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Intake leak only when cold (gasket shrinks)Common
- IAC valve sticking when coldPossible
Parts involved
- Idle Air Control Valve
- Cold Start Strategy
- Intake Manifold Seal
P050A 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.