Possible causes

– Idle Air Control Solenoid valve harness is open or shorted
– Idle Air Control Solenoid valve circuit poor electrical connection
– faulty Idle Air Control Solenoid valve

Symptoms

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

P1516 SUBARU Description

The Idle Air Control Solenoid valve is incorporated in the throttle body and regulates the amount of intake air which bypasses the throttle valve built into the throttle body. It is activated by a signal sent from the Engine Control Module (ECM) to maintain engine idle speed to the target engine speed.