How to Change a Battery in a BMW Key fob

You press the unlock button and nothing happens. That tiny moment of panic? It usually just means the battery inside your BMW key fob needs to be replaced. The good news? You don’t need tools, special training or much time. Just a steady hand, a new battery, and this simple guide.

First, Know Which Key You Have

Most newer BMW vehicles in Canada come with Comfort Access keys. These usually take a CR2032 battery. Some older models use CR2450. The best way to know? Pop the fob open and check the size on the old battery before buying a replacement. 

How to Open It Without Stressing Out

Start by pressing the small tab on the back of your key fob. This releases the metal key hidden inside. Remove it and set it aside. Now, you’ll see a small gap where the key was stored. Use that same key—or a small flathead screwdriver wrapped in tape—to gently pry open the fob. It should come apart without much force. If it doesn’t open, you might have a rechargeable key that needs professional help. That’s rare, but it does happen.

Out With the Old, In With the New

Once the fob is open, carefully remove the old battery. Note which side is facing up. Most of the time, the positive side (the one with the writing) faces outward. Replace it with the new battery in the exact same position. Once it’s in, press the fob back together. It should snap closed easily. Then slide the metal key back into place.

Still Not Working? Here’s What to Do

Sometimes, after a battery swap, the key might need to be re-paired with your BMW. This is more common in models with Comfort Access or remote start. If the buttons still don’t work, come visit us at Policaro BMW. We’ll help reprogram it so it works like new again.

Why This Matters More in Canada

Cold mornings in Ontario can be tough. That’s why features like BMW Remote Start or Comfort Access are such lifesavers. A working key fob means your car is ready to heat up before you even step outside. It’s not just about unlocking the door—it’s about comfort and convenience, especially when winter hits Brampton.

Need Help or a New Battery? We’ve Got You

Stop by Policaro BMW in Brampton, ON and let our team help with your key fob. Whether you need a fresh battery, help pairing your key, or a full replacement, we’re here to make it simple. We’re more than a dealership. We’re part of your drive.