2004 BMW X3 2.5i

1. Close all doors.
2. Insert key into ignition.
3. Turn the key to position 1 and back off five times very quickly.
4. Remove key from ignition.
5. Hold down the unlock button on the remote to be programmed and while holding down the unlock button press the lock button 3 times, then release the unlock button. Shortly after releasing the unlock button the door locks will cycle signalling successful programming of the remote. (If they do not cycle open the door and return to step one.)
6. If you have another remote repeat step 3 with the second remote within 30 seconds. (Up to 4 remotes)
7. Reinsert key into ignition and turn to on and back off to finalise.