- Idle Air Control (IAC) valve: The IAC valve is responsible for controlling the amount of air that bypasses the throttle body at idle. A faulty IAC valve can cause the idle speed to fluctuate.
- Throttle position sensor (TPS): The TPS sends a signal to the engine control unit (ECU) indicating the position of the throttle. A faulty TPS can cause the ECU to send incorrect signals to the IAC valve, resulting in idle speed fluctuations.
- Vacuum leaks: Vacuum leaks can cause the engine to run lean, which can also lead to idle speed fluctuations. Check for any loose or cracked vacuum hoses.
- Oxygen sensor: The oxygen sensor monitors the amount of oxygen in the exhaust gas and sends a signal to the ECU. A faulty oxygen sensor can cause the ECU to send incorrect signals to the fuel injectors, resulting in idle speed fluctuations.
- Bad fuel injector: Leaking fuel injectors can cause the engine to run rich, which can also lead to idle speed fluctuations.
If you're not comfortable diagnosing and repairing the problem yourself, I recommend taking your car to a qualified mechanic for further diagnosis.
