Method and system for authenticating vehicle equipped with passive keyless system

A system and method is provided for authenticating a vehicle equipped with a passive keyless system. The method includes sending one or more initial challenge signal(s) from a vehicle module to a portable keyfob in response to a passive keyless start attempt of the vehicle, the initial challenge signal(s) being sent before a successful passive keyless start of the vehicle; sending one or more secondary challenge signal(s) from the vehicle module to the portable keyfob in response to at least one trigger event and after a successful passive keyless start of the vehicle; initiating an active authentication to confirm the presence of an authorized driver in the vehicle if a valid response to the secondary challenge signal(s) is not received by the vehicle module; and performing one or more remedial action(s) if a valid response to the active authentication is not received.