How to replace the battery in an old BMW 5 Series key?
2 Answers
Flip the car key over to the back, where you will see a small button; press it. Grab the key handle on top and pull it upwards to remove it, revealing the metal mechanical key. Use the removed mechanical key to pry open the car key cover. Once a gap appears, apply a bit of force to open it. Remove the old battery and replace it with a new one. Then, reattach the car key cover and insert the mechanical key back into place.
Last month I just replaced the key battery for my old 5 Series at home, and it was actually quite simple. The old BMW 5 Series keys usually have that flip-open design, with the battery compartment hidden under the back cover. First, locate the small notch on the side of the key, then gently pry open the back cover using a coin or small blade. You'll see a small round button battery inside, which is a CR2032 model - easily available at auto parts stores or the electronics section of supermarkets. When replacing, pay attention to the positive and negative polarity; don't install it backwards (the old battery has markings). After inserting the new battery, press the back cover until you hear a click. The whole process takes less than five minutes, and doing it yourself saves you hundreds compared to going to the dealership. Remember to handle it gently to avoid breaking the plastic clips, and after replacement, test whether the unlock button responds normally.
