Passive Anti-Theft System (PATS) - Without Intelligent Access (IA): Overview
WARNING: This page is about a different car, the 2013 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
PATS protects the vehicle from theft by preventing the engine from starting unless a programmed PATS key is in the ignition. PATS cannot disable an already running engine.