Replace BMW Key Battery It's probably the time to change your battery If your BMW key won't open your car or turn off the engine. It's a simple fix. You simply need to remove the key fob, then replace the battery, and then gently put it back. Follow these steps https://thekeylab35194.ourcodeblog.com/30301327/the-biggest-problem-with-bmw-3-series-key-fob-and-how-you-can-solve-it