Idle Air Control System RPM Lower Than Expected
The engine idles below the target RPM despite the IAC opening fully. Indicates restricted air path past the IAC — typically a heavily fouled throttle body or stuck IAC valve.
Affected components
- Idle air control valve
- Throttle body
Common causes
- High likelihood: Throttle body or idle bypass passage clogged
- Medium likelihood: IAC valve stuck mostly closed
Possible symptoms
- Check engine light on
- Idle speed too high, too low, or unstable
- Possible stalling at idle or after cold start
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.