The idle speed stays above the target. The driver may notice a fast idle and a car that pulls forward in gear.
Causes vary by car. Test before you order a part.
Likely causes, most common first
- Vacuum leak
- Dirty or sticking throttle body
- Faulty idle air control valve
- Leaking PCV hose
Parts usually involved
- Intake gaskets Find at suppliers
- Throttle body Find at suppliers
- Idle air control valve Find at suppliers
- PCV valve Find at suppliers
Test before you replace
Smoke test the intake for vacuum leaks and check the throttle plate closes correctly.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.