P1508moderate severityPowertrain

Idle Air Control System RPM Too Low

on 2008 Buick Enclave 3.6L V6 · AWD

What this code means

The PCM detected that the engine idle speed is lower than the specified minimum range and the Idle Air Control (IAC) system is not responding to correct it.

Symptoms

  • Low idle speed
  • Engine stalling at idle
  • Rough idle
  • Difficulty keeping engine running
  • Stalling when coming to a stop

Common causes

  • Faulty IAC valve
  • Dirty or carbon-clogged IAC valve
  • Vacuum leak
  • Dirty throttle body
  • Electrical issue with IAC circuit
  • PCM failure (rare)

Diagnostic steps

  1. Inspect IAC valve for carbon buildup
  2. Clean throttle body
  3. Check for vacuum leaks
  4. Test IAC valve operation
  5. Monitor IAC counts with scan tool
  6. Check wiring to IAC valve

Repair notes

Clean IAC valve and throttle body. If cleaning does not resolve, replace IAC valve. Check for vacuum leaks.

Other Powertrain codes on this vehicle

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