How do you programme 1998 Audi a3 key?

To program a 1998 Audi A3 key, you'll need the original key and a new key that is compatible. Insert the original key into the ignition and turn it to the "On" position without starting the engine. Within 10 seconds, remove the key and insert the new key, turning it to the "On" position as well; the immobilizer light should turn off, indicating successful programming. If you have difficulty, consulting the vehicle's manual or a professional locksmith may be necessary.