2005 Subaru Impreza Owner's Manual - Page 106

Keys and doors The valet key fits only the ignition switch and driver's door lock. You can keep the trunk and glove box locked when you leave your vehicle and valet key at a parking facility. Immobilizer (WRX-STi) The immobilizer system is designed to prevent an unauthorized person from starting the engine. Only keys registered with your vehicle's immobilizer system can be used to operate your vehicle. Even if an unregistered key fits into the ignition switch and can be turned to the "START" position, the engine will automatically stop after several seconds. Each immobilizer key contains a transponder in which the key's ID code is stored. When a key is inserted into the ignition switch and turned to the "ON" position, the transponder transmits the key's ID code to the immobilizer system's receiver. If the transmitted ID code matches the ID code registered in the immobilizer system, the system allows the engine to be started. Since the ID code is transmitted and acted upon almost instantly, the immobilizer system does not impede normal starting of the engine. If the engine fails to start, pull out the key once before trying again. (Refer to the "Ignition switch" section [chapter 3].) Do not attach a large key holder or key case to either key. If it banged against your knees while you were driving, it could turn the ignition switch from the ON position to the ACC or OFF position, thereby stopping the engine. Key number The key number is stamped on the metal plate attached to the key set. Write down the key number and keep it in another safe place, not in the vehicle. This number is needed to make a replacement key if you lose your key or lock it inside the vehicle. NOTE To protect your vehicle from theft, please pay close attention to the following security precautions: - CONTINUED - 2-3