- Faulty idle air control (IAC) valve: The IAC valve controls the amount of air that bypasses the throttle body when the engine is idling. A faulty IAC valve can cause the engine to stall when put into gear, as it is unable to maintain a consistent idle speed.
- Vacuum leak: A vacuum leak can cause the engine to run lean, which can lead to stalling. Check for any loose or disconnected vacuum hoses, and make sure that the intake manifold is properly sealed.
- Dirty throttle body: A dirty throttle body can cause the engine to stall by blocking the airflow into the engine. Clean the throttle body using a throttle body cleaner and a soft cloth.
- Faulty fuel injector: A faulty fuel injector can cause the engine to run lean or rich, which can lead to stalling. Check the fuel injectors for any clogs or leaks, and replace them if necessary.
- Transmission problems: If the transmission is not shifting properly, it can cause the engine to stall. Check the transmission fluid level and condition, and make sure that the transmission is shifting smoothly.
If you are unable to identify the cause of the problem yourself, it is best to have a qualified mechanic inspect the vehicle.
