Information related immobilizer,that are classified as 2(two) parts independently, is memorized in EEPROM. PCM/ECM check these 2(two) information berfore proceeding immobilizer authentication. With synchronized both information, PCM/ECM starts immobilizer authentication procedure. If both information is not synchronized, PCM/ECM stops immobilizer authentication, Limphome function will not be activated, and memorizes DTC P1695. If DTC P1695 is retrieved again, after performing new key teaching procedure, PCM/ECM should be replaced with new one.