Abstract: An anti-theft car protection system comprises a transmitter-receiver for receiving a code of the key, an immobilizer unit for collating said code as received with a code as registered and transmitting an engine start permission signal to an engine control unit when said code as received coincides with said code as registered, and means, cooperating with said immobilizer unit, for removing repetition of key operation upon start of the engine.

Abstract: An antitheft apparatus for an automotive vehicle comprises: a transponder (1) buried in an ignition key to store an ID number thereof; a receive unit (2) to receive the ID number of the ignition key inserted into the ignition key cylinder; an immobilizer unit (3) for outputting an engine start enable signal when the received ID number matches one of the stored ID numbers and not outputting the engine start enable signal when does not match; and an engine control unit (5) for enabling an engine drive in response to the reception of the engine start enable signal but disabling the engine drive in response to no reception of the engine start enable signal. In particular, the engine drive unit (5) keeps the immobilizer unit (3) inoperative for a predetermined time duration when the engine cranking operation is detected and allows the immobilizer unit (3) to be operative after the predetermined time has elapsed.