What this code means

The IAC system has reached its maximum adaptive correction and can no longer maintain proper idle speed. This indicates the IAC is working at its limit trying to compensate for another issue.

Symptoms

• Check Engine Light
• Idle speed too high or too low
• Rough idle
• Stalling

Common causes

• Large vacuum leak
• Carbon buildup restricting airflow
• Faulty IAC valve
• Throttle body needs cleaning
• Air leak in intake system

Diagnostic steps

1. Check for vacuum leaks using smoke test
2. Clean throttle body and IAC passage
3. Monitor IAC duty cycle — near 0% or 100% indicates problem
4. Inspect for air leaks in intake system

Repair notes

Find and fix the root cause (usually vacuum leak or carbon buildup). Clean throttle body. Replace IAC if valve itself is faulty.

Other Powertrain codes on this vehicle