Replace BMW Key Battery If your BMW key isn't able to open your car or turning over the engine, it may be time to replace your battery. Fortunately, it's a simple fix. You simply need to remove the key fob, then replace the battery, and then gently put it back. https://carkeyreprogramming75222.blogstival.com/52625457/why-all-the-fuss-over-bmw-key-fobs