Idle Air Control System RPM Too Low
2002-2009 GMC Envoy 4.2L I6 🇩🇪
Description
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
- Inspect IAC valve for carbon buildup
- Clean throttle body
- Check for vacuum leaks
- Test IAC valve operation
- Monitor IAC counts with scan tool
- 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.
Related Codes
Other Powertrain Codes
- P0001Fuel Volume Regulator Control Circuit/Open
- P0001Fuel Volume Regulator Control Circuit/Open
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0003Fuel Volume Regulator Control Circuit Low
- P0003Fuel Volume Regulator Control Circuit Low
- P0004Fuel Volume Regulator Control Circuit High
- P0004Fuel Volume Regulator Control Circuit High
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
P1508 on Other Vehicles
Common Questions
What does code P1508 mean on a 2002-2009 GMC Envoy?
P1508 stands for "Idle Air Control System RPM Too Low". 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.
What are the symptoms of P1508 on a GMC Envoy?
Common symptoms of P1508 include: Low idle speed, Engine stalling at idle, Rough idle, Difficulty keeping engine running, Stalling when coming to a stop.
What causes P1508 on a 2002-2009 GMC Envoy?
Common causes of P1508 include: Faulty IAC valve, Dirty or carbon-clogged IAC valve, Vacuum leak, Dirty throttle body, Electrical issue with IAC circuit, PCM failure (rare).