Circuit Description

The rotary solenoid type idle air control (IAC) valve is located under the throttle body and intake air bypassing the throttle valve flows into the IAC valve through the passage.

In this way the intake air volume bypassing the throttle valve is regulated, controls the engine speed.

The ECM operates the IAC valve only to perform idle-up and provide feedback for the target idling speed.

Fig 1: Identifying Idle Air Control System - Circuit Description

DTC DETECTION CONDITION

DTC No.	DTC Detecting Condition	Trouble Area
P0505	Idle air continues to vary greatly from target speed (2 trip detection logic)	Open or short in idle air control (IAC) valve circuit Idle air control (IAC) valve is stuck or closed A/C switch circuit Air induction system PCV valve and hose ECM
P0511	Open or short ISC circuit