Replace BMW Key Battery It could be time to replace your battery if your BMW key won't allow you to 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 gently put it back. Follow https://car-key-programming36071.thelateblog.com/30679564/are-you-getting-the-most-out-of-your-bmw-3-series-key-fob