1) Idle Air Control Valve (IACV): The IACV is responsible for controlling the amount of air that bypasses the throttle plate when the engine is idling. If the IACV is faulty or dirty, it can cause the engine to idle high.
2) Vacuum leak: A vacuum leak can cause the engine to run lean, which can lead to a high idle. Vacuum leaks can occur in a variety of places, such as the intake manifold, throttle body, or vacuum hoses.
3) Throttle Position Sensor (TPS): The TPS tells the engine's computer how far open the throttle plate is. If the TPS is faulty, it can send the wrong signal to the computer, which can cause the engine to idle high.
4) Dirty throttle body: A dirty throttle body can restrict the flow of air into the engine, which can cause the engine to idle high.
5) Fuel injector problem: A faulty fuel injector can cause the engine to run rich, which can lead to a high idle.
6) PCV valve: A faulty PCV valve can cause excessive crankcase pressure, which can lead to a high idle.
If you are experiencing a high idle, it is important to have it diagnosed by a qualified mechanic. They will be able to determine the cause of the problem and recommend the best course of action.
