An idle air control (IAC) valve is a device that regulates the amount of air that bypasses the throttle valve when the engine is idling. This helps to maintain a smooth and stable idle speed. A faulty IAC valve can cause a variety of problems, including rough idling, stalling, and poor fuel economy.
There are a few different ways to check an IAC valve. One method is to use a scan tool. A scan tool can be used to read the data from the IAC valve and to determine if it is functioning properly. Another method is to use a multimeter to test the electrical resistance of the IAC valve. If the resistance is out of specification, the IAC valve may need to be replaced.
