How do I reset the anti theft in the 2002 ford expedition?

To reset the anti-theft system in the 2002 Ford Expedition You will need to be sure to use the passive anti-theft system key that came with the car. When using a different key that has not been progRammed the car will go into armed mode. If the correct key does not disarm the system You should next try the spare if available. If the problem persists, disconnect the battery waiting 15 minutes before reconnecting and trying both keys again. If the car still fails to start You will need to have it checked by a professional.