P1506 – Idle Air Control Overspeed Error

P1506 Possible Symptoms

Engine Light ON (or Service Engine Soon Warning Light)

P1506 Possible Causes

Faulty Idle Air Control (IAC) valve,IAC valve harness is open or shorted,IAC valve circuit poor electrical connection,Intake leaks,Stuck PCV Valve

P1506 Description

The Idle Air Control Valve (IACV) valve assembly controls the engine idle speed and provides a dashpot function. The IAC valve assembly meters intake air around the throttle plate through a bypass within the IAC valve assembly and throttle body. The Powertrain Control Module (PCM) determines the desired idle speed or bypass air and signals the IAC valve assembly through a specified duty cycle. The IAC valve responds by positioning the IAC valve to control the amount of bypassed air. The PCM monitors engine RPM and increases or decreases the IAC duty cycle in order to achieve the desired RPM.