Idle Air Control Overspeed Error

What this code means

The engine idle speed is too high. The PCM has detected that idle RPM exceeds the target idle speed and the IAC system cannot bring it down. The engine may be idling at 2000+ RPM.

Symptoms

• Check Engine Light
• Idle speed too high
• Engine races at idle
• Vehicle creeps forward in gear

Common causes

• Vacuum leak (most common)
• IAC valve stuck open
• Throttle plate not closing fully
• Throttle body carbon buildup preventing closure
• Faulty IAC valve
• Intake manifold gasket leak

Diagnostic steps

1. Check for vacuum leaks with engine running — spray carb cleaner around intake
2. Inspect throttle body for carbon preventing plate closure
3. Test IAC valve — disconnect and check if idle drops
4. Clean throttle body and IAC passages
5. Inspect intake manifold gaskets

Repair notes

Find and repair vacuum leak. Clean throttle body. Replace IAC valve if stuck open.

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