1. Idle Air Control (IAC) Valve Issues: The IAC valve regulates the amount of air that bypasses the throttle body when the engine is idling. If the IAC valve is faulty or dirty, it can cause the engine to idle too low.
2. Vacuum Leaks: Vacuum leaks can cause the engine to run lean and lead to a low idle. Check for leaks in the intake manifold, hoses, and other vacuum lines.
3. Dirty Throttle Body: A dirty throttle body can restrict airflow and cause the engine to idle too low. Remove the throttle body and clean it with throttle body cleaner.
4. Fuel Delivery Problems: Issues with the fuel system, such as a clogged fuel filter or a faulty fuel pressure regulator, can cause the engine to idle too low. Check fuel pressure and replace any faulty components as needed.
5. Faulty Sensors: Sensors like the oxygen sensor, throttle position sensor, or coolant temperature sensor can provide incorrect information to the engine control unit (ECU), which can affect idle speed. Test these sensors and replace them if necessary.
6. Mechanical Issues: In rare cases, mechanical problems like a worn camshaft or valve issues can cause the engine to idle too low. If the issue persists despite addressing other potential causes, consult a qualified mechanic.
