Like many BMW 328i owners, I decided to replace the battery in my key fob to address the low battery warning displayed on the dashboard. I researched online and found guides suggesting that replacing the battery in a BMW key fob involves opening the case and replacing the soldered battery. I even purchased a new shell case for my key fob, thinking it would simplify the process and provide a fresh look, avoiding the need to glue the original case back together.
Following a video tutorial, I proceeded to replace the original VL2020 Panasonic battery with a new ML2020 Panasonic battery. However, after the replacement, my BMW 328i key fob stopped working correctly. While the key fob still starts the car, it no longer locks or unlocks the doors or the trunk.
To ensure the new battery wasn’t faulty, I tested it with a multimeter, and it registered a normal 3 Volts. Troubleshooting further, I even reinstalled the original VL2020 battery, which was working perfectly fine before the replacement, but now it also fails to operate the lock/unlock functions. I even tried using the key chip without any casing, suspecting pressure from the new case might be causing the issue, but the problem persisted.
I’m now at a loss to understand what went wrong during this seemingly straightforward BMW 328i key fob battery replacement. Has anyone experienced a similar issue after replacing their BMW 328i key fob battery? Could there be something I overlooked or a step I missed during the battery replacement process that caused the key fob to stop controlling the door locks and trunk? Any advice or insights on what might be happening or how to resolve this issue with my BMW 328i key fob would be greatly appreciated.
