I’m often asked how to do this.
This applies to all EWS remote central locking with three button remotes, so E38/39/46/53, X3, Z3, Z4, Range Rover, Mini etc.
Synchronise BMW EWS Remote Central Locking
Sit in the car with the doors closed and unlocked and the windows closed.
Have all the keys you want to synch with you.
Turn the key to position one – dash lights on, but ignition lights not on.
Remove the key.
Hold unlock. Press lock three times and release both simultaneously.
The locks should cycle. Now do the same for all other keys – you don’t need to put them in the ignition, just press the buttons.
With some later gms, I’ve had to fully switch the ignition on and with some aftermarket keys, you have to press lock several times.
I can supply a new Diamond key for £80. BMW are about £160.00+ VAT