Antenna Unit, Immobilization: General: Function
WARNING: This page is about a different car, the 2002 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.
The standard equipment on the car includes a system that prevents starting of the car unless the correct key is used. There is a transponder in the key with an identification code that is unique to that particular transponder. The receiver receives the identification code and sends it on to TWICE.