Replace BMW Key Battery If your BMW key isn't able to open your car or turning on the engine, it may be the time to replace your battery. Fortunately, it's an easy fix. All you have to do is take off the cover of the key fob take it off, https://the-key-lab61089.diowebhost.com/85207518/this-is-the-complete-listing-of-bmw-key-fobs-dos-and-don-ts