* Idle air control valve (IAC): The IAC valve is used to control the amount of air that flows into the engine at idle. A faulty or dirty IAC valve can cause the engine to idle high or low.
* Throttle position sensor (TPS): The TPS is used to control the fuel injection system. If the TPS is faulty or dirty, it can cause the engine to idle high or low.
* Manifold absolute pressure (MAP) sensor: The MAP sensor is used to measure the amount of air pressure inside the intake manifold. A faulty or dirty MAP sensor can cause the engine to idle high or low.
* Faulty spark plugs or wires: Faulty spark plugs or wires can cause the engine to idle high or low. Worn or damaged spark plugs and wires can result in a misfire, which can cause the engine to idle high or low.
* A failed O2 sensor: Oxygen sensors are used to monitor the amount of oxygen in the exhaust. A failed O2 sensor can cause the engine to run rich, which will cause the idle to be high.
* Clogged or dirty throttle body: A clogged throttle body will restrict the amount of air that can flow into the engine. This can cause the engine to idle high or low.
