One forum post says:
"The EWS controls the signal from the key to the injection system. If the key doesn't match the stored code in the EWS brain the car will not start."
EWS is apparently a German acronym for Electronic Immobilization System or Driveaway Protection System or antitheft system. The Bentley Manual says a primary code is imbedded in the key and the vehicle and a secondary code is changed every time the vehicle is started. If the key code and EWS module do not match, the engine management module and starter are disabled. And it is possible to damage the electronics in the key rendering it unusable.
Here's some stuff on EWS:
Last edited by vintage42; 01-02-2013 at 05:11 AM.