Possible causes

– Faulty Idle Air Control Valve
– Vacuum leak
– Idle Air Control Valve harness is open or shorted
– Idle Air Control Valve circuit poor electrical connection

Tech notes

Clean Idle Air Control Valve (IACV)

– Warm up Engine
– Remove the intercooler and set aside
– Disconnect the Mass Airflow sensor connector
– Cycle the key “On/Off” once
– Start the car and maintain engine speed between 1000-1500rpm
– Spray engine cleaner on the upper air-stream of the throttle chamber for approximately 10 seconds
– Step engine and let sit for 3 minutes
– Restart engine and maintain 1000 to 1500 rpms
– Spray Engine cleaner on the upper air-stream of the throttle chamber for approximately 10 seconds
– Turn engine off
– Reinstall intercooler and reconnect Mas Airflow sensor connector
– Operate car between 1000-2000rpms until no white smoke appears through tailpipe
– Turn ignition switch off and clear memory

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)