DTC P0505 Idle Control System Malfunction; DTC P0511 Idle Air Control Circuit: Description

The Idle Air Control (IAC) valve, a rotary solenoid type, is located under the throttle body. Intake air bypassing the throttle valve flows into the IAC valve through a passage.

The valve regulates the volume of intake air that bypasses the throttle valve and allows the engine idling speed to be controlled.

The IAC valve is used by the ECM to perform idle-up and its feedback signal is used as one factor in target engine idling speed regulation.

Fig 1: Idle Air Control Circuit Diagram

DTC DETECTION CONDITION CHART

DTC No.	DTC Detection Condition	Trouble Area
P0505	Engine idling speed continues to vary greatly from target idling speed (2 trip detection logic)	Open or short in IAC valve circuit IAC valve stuck or closed A/C switch circuit Air induction system Ventilation valve and hose ECM
P0511	Open or short IAC valve circuit (1 trip detection logic)	Open or short in IAC valve circuit IAC valve stuck or closed ECM