I cannot recall which of these resolved the issue with my X key, but as previously stated, the key charges the ignition when driving.
BMW X5 - Programming Key Remote
Three strategies to try:
Method 1:
Working from inside the vehicle with the hatches closed
Within 5 seconds, turn the ignition to position 1 and then off again.
Remove the key from the ignition and press and hold the unlock button for 15 seconds; then, within 5 seconds, press the key lock button three times.
4. Let go of both keys.
Doors will close and release to demonstrate precise programming.
Method 2:
For this procedure, you will need one functional key and one key that requires programming.
1) Enter and secure all doors.
2) Turn the ignition on and off rapidly. (No longer than five seconds) to initiate the procedure. The next action must occur within 30 seconds.
3) Eliminate the first key.
4) Hold the button near your left shoulder so that it is closer to the antenna of the remote receiver.
5) Maintaining the unlock button depressed, press the lock button three times. When the unlock button is released, the doors secure, confirming the operation.
6) Repeat steps 4 and 5 for the second key, etc.
If it does not work, try pressing the keys backwards. Instead of 1 then 2, press 2 then 1.
Method 3:
Alternate if you lack a functional remote
Quickly turn the key to position 1 five times 2. Remove the key 3. Hold the unlock button, then press the lock button three times, and then release the unlock button.
4. If you have another key, select the identical button within 30 seconds 5.Start the engine to conclude.
NOTE: This programming procedure programmes the key's remote control feature. A specialist is required to programme any transponder device for the immobiliser (car beginning).