Replace BMW Key Battery If your BMW key isn't opening your car or turning on the engine, it could be the time to replace your battery. Fortunately, it's an easy fix. You simply need to remove the key fob, then replace the battery, and then gently put it back. Follow https://carkeyreprogramming51413.mdkblog.com/35865092/the-history-of-bmw-3-series-key-fob