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)
– Engine rough idle
– Engine rough idle
P1508 ACURA OBD Code Description
The target idle speed is in the Engine Control Module (ECM) memory for various engine conditions (coolant temperature, A/C operation and so on). The ECM keeps the actual idle speed at the target idle speed by switching the Idle Air Control Valve IACV) ON/OFF to control the intake airflow. If the IACV output duty cycle (the length of ON time) is out of a specified range,
a malfunction is detected and a DTC is stored.