Replace BMW Key Battery It's probably time to replace your battery if your BMW key won't allow you to open your car or turn on the engine. It's a simple fix. It's as easy as removing the key fob, replace the battery and gently put it back. Follow these steps https://car-key-replacement20710.tblogz.com/what-is-the-best-way-to-spot-the-bmw-key-fobs-which-is-right-for-you-44198523