P1504 Intake Air Control Circuit Malfunction
Possible causes
– Idle Air Control Valve harness is open or shorted
– Idle Air Control Valve circuit poor electrical connection
– Faulty Idle Air Control Valve
– Idle Air Control Valve circuit poor electrical connection
– Faulty Idle Air Control Valve
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P1504 Description
The Idle Air Control Valve (IACV) is used to control engine idle speed and allows air to bypass the throttle plate. The amount of air allowed to bypass is determined by the Powertrain Control Module (PCM) and controlled by a duty-cycle signal.