A BMW remote key may have a wide variety of functions, from locking and unlocking the vehicle to programming the vehicle with specific climate preferences. Remote key fobs vary depending on the year and model of the BMW. Instructions for replacing the remote key battery are included in the BMW owner's manual, to which you can refer for model-specific instructions. To replace the battery in your remote key fob, you will need a replacement battery that matches the one now in your remote.
Ensure that the battery in your remote key fob is truly dead. The batteries in BMW's remotes automatically recharge when the remote key is present and the vehicle is running. If the remote key fob seems to have a dead battery, try to recharge it by taking a long drive.
Remove the integrated key, if your remote key is designed with an integrated key. Remove the key by pressing the ridged button at the edge of the fob and pressing it outward. The integrated key will pop free from the remote key fob.
Slide the cover off from the back of the remote key fob. The cover is half the size of the fob and can be removed by placing a small amount of pressure while sliding the cover away from the fob.
Take the old battery out of the remote key fob and dispose of it by returning it to your BMW dealer.
Place the new battery into the remote key fob by pushing it into place, with the positive side of the battery facing up.
Slide the cover back into place until it is secure and replace the integrated key into the fob, if appropriate.
If you have replaced the battery in your remote key fob and the key is still not working correctly, contact your BMW dealer for assistance. For instructions specific to the model of BMW that you own, refer to the owner's manual. A warning light may be present on your dash to indicate when your remote key battery needs to be replaced.