- Idle air control valve (IAC)- The IAC valve regulates the amount of air that bypasses the throttle body when the engine is idling. If the IAC valve is faulty, it can cause the engine to idle too high.
- Vacuum leak- A vacuum leak can cause the engine to run lean, which can lead to high revs. Some common places for vacuum leaks include the intake manifold gasket, throttle body gasket, and brake booster hose.
- Throttle position sensor (TPS)- The TPS sensor tells the engine control unit (ECU) the position of the throttle. If the TPS sensor is faulty, it can send incorrect signals to the ECU, which can cause the engine to idle too high.
- Fuel injector- A faulty fuel injector can cause the engine to run rich, which can lead to high revs.
- Clogged air filter- A clogged air filter can restrict airflow to the engine, which can cause the engine to run lean and lead to high revs.
