The idle air control (IAC) valve is located on the throttle body of fuel-injected engines, where it works with the vehicle's ECU to electrically regulate airflow to the engine to ensure smooth idling.
How do you test an IAC valve?
Can IAC valve cause no start?
the car won't start: in extreme cases, the iac valve may cause too much or too little air from entering the engine when you turn the ignition, resulting in engine that cranks but doesn't start.
What will a bad IAC valve do?
The idle air control valve is programmed to regulate and maintain the engine idle speed at a constant rate. If the valve fails or has any issues it can cause the idle speed to be thrown off. This may result in an unusually high or low idle speed, or in some cases a surging idle speed that repeatedly climbs and falls.
Related Question How does an IAC valve work?
How much does a idle air control valve cost?
The replacement cost of an idle control valve is anywhere from $120 to $500. The cost of the parts alone will be between $70 and $400+, depending on the make and model of your vehicle. The labor cost should only be around $50 to $100 because it doesn't take that long to remove and replace the old idle control valve.