The 2005 BMW X5 comes with an ignition key that has a keyless entry control designed directly into the key. However, the controls won't work correctly if a replacement key is ordered. You'll need to program the key in the correct sequence. Although replacement ignition keys can only be ordered from a BMW dealer, you can program the key yourself and save money.
Enter the BMW X5. Shut the door. Put the key in the ignition and turn it to the "ACC" position on the lock cylinder.
Move the ignition key to the "OFF" position. Take the key out of the ignition. Press down on the key's "Unlock" button. Release the "Lock" button. Do this three separate times within five seconds. Let go of the "Unlock" button. The locks on the car door will now unlock.
Press down on the "Unlock" button if you wish to reprogram another new key. Let go of the "Lock" button. Again, do this three times inside of five seconds. Let go of the "Unlock" button. Confirm that the locks on the door unlock and lock on your command.