When you need to replace the BMW remote key battery, the old battery is running out of juice, making it impossible to easily unlock the door, securely lock it, and eject the trunk. Thankfully, you can get it working again by replacing it with a new battery. All you need is a screwdriver and the right batteries.

What battery does the BMW key fob use?

Well, that depends on which BMW key fob you have. The smart key uses the CR2450, while the comfort access and sleek, slant-shaped fobs require the CR2032. The other key fob styles have non-replaceable batteries.

Where can I find a new battery and how much will it cost?

You can find CR2450 and CR2032 3-volt batteries at office supply stores, hardware stores, or other local retailers. Just look at the battery section near the other button batteries.

If you have a diamond key fob or non-comfort access remote, you cannot easily replace the batteries. The non-comfort access model is rechargeable and should refill its battery while you drive. Once that battery wears out, you have to buy a new key fob.

When the battery is exhausted, the diamond keychain also needs to be replaced, because it is impossible to replace the battery connection without soldering. Your local distributor can help you replace these key fobs, although they may need to order them if they are not in stock.

How to Replace the BMW Key Fob Battery

When it comes to the BMW key fobs with replaceable batteries, the replacement process is quite similar for each one. Just follow these steps to get the job done.

1. Pull out the Metal Key

You must remove the metal key before opening the case to obtain the internal battery. Locate the button near where the key is ejected from the shell. Then, press the key while gently pulling it out of the case.

The entire key assembly should pull free with ease. If you feel any resistance, push down on the button more and try again.

2. Eject and open the chassis

Looking at the end of the case, the key is a small open area along the seam. Insert the tip of the flat head screwdriver into the opening and carefully pry it up.

The case should be immediately separated to reveal the battery inside. If not, reposition the screwdriver and repeat the process until the housing is opened.

3. Remove and replace the old battery

With a screwdriver in hand, pry open the underside of the battery and slowly pull it out of the pit. Immediately put old batteries in a trash can out of reach of children and pets.

Put in the new battery and make sure it faces the same direction as the old one. The battery doesn't click in place, so hold the remote steady while you reassemble the case.

4. Reassemble the Case and Test

Put the case back together by lining up both sides and squeezing them together. You should hear a light click when it seats back in place. Then, you can push the metal key section back into the rest of the case to complete the battery change process.

Once you have your key fob reassembled, head outside to your 2016 X6 or other BMW to see if it works. Make sure to hit each button and verify that the car unlocks, pops the trunk, and completes all the other expected tasks. If it doesn't work right, plan to make a trip to the dealership to see if you need to replace the key fob outright.