You can replace a BMW key fob battery yourself in about five minutes with a coin and a replacement battery

BMW key fobs use a coin cell battery that sits behind the fob's plastic case. You do not need tools beyond a coin or flathead screwdriver, and the battery costs between $3 and $8 at most pharmacies, supermarkets, or electronics stores. The whole job takes longer to find the right battery type than to swap it out.

The steps are the same across most BMW models from the past 15 years, though some newer fobs with touch buttons may have a slightly different case design. If your fob has physical buttons, the process below will work.

Key Takeaways

  • BMW key fobs use a CR2032 or CR2025 coin cell battery, which you can buy at any pharmacy or grocery store for under $10.
  • Open the fob by inserting a coin into the slot on the side and twisting gently until the case separates into two halves.
  • Note which side the battery sits on before you remove it, because the positive side must face up when you put the new one in.
  • After inserting the new battery, press the two halves back together until you hear or feel a click, then test the fob before you leave the store.

Finding the right battery type for your BMW fob

Most BMW key fobs use either a CR2032 or CR2025 battery. The easiest way to know which one yours needs is to look at the old battery after you open the fob — the type is printed on the metal side. If you want to know before you open it, check your owner's manual or call your BMW dealer with your vehicle identification number (VIN).

CR2032 is the more common type and fits most BMW fobs made in the last 15 years. CR2025 is slightly thinner and appears in some older models. Both cost the same and are sold in the same aisle at pharmacies and supermarkets. Buy a pack of two so you have a spare, since these batteries last three to four years and you will eventually need another one.

Opening the key fob case

Look at the edge of your BMW key fob. You will see a small slot or seam running along one side. This is where the two halves of the case meet. Insert a coin — a dime or penny works — into that slot, or use a flathead screwdriver if you do not have a coin handy.

Turn the coin gently, as if you were opening a battery compartment on a toy or remote control. Do not force it. The case will separate into two pieces after a quarter turn or less. If it does not budge after gentle pressure, try a different spot along the seam — sometimes the slot is not obvious on the first try.

Once the case opens, you will see the battery sitting in a small metal holder. It looks like a silver disc about the size of a dime. Do not touch the metal contacts on either side of the battery, as oils from your skin can interfere with the connection.

Removing and replacing the battery

Before you remove the old battery, note which side is facing up. The positive side (marked with a + symbol) should face up in the holder. This matters because if you install the new battery upside down, the fob will not work.

Gently pry the old battery out of its holder using your fingernail or the edge of a coin. Drop it aside — you do not need to keep it. Take your new battery and place it in the same position as the old one, with the positive side facing up. Press it down gently until it sits flat in the holder.

Closing the fob and testing it

Align the two halves of the case so the seam matches up evenly. Press them together firmly until you hear a small click or feel them snap into place. The case should feel solid and not have any gaps or loose edges.

Before you leave the store or go home, test the fob by pressing each button — lock, unlock, and panic if your model has one. Point it at your car from a few feet away and watch for the lights to flash or hear the locks respond. If nothing happens, open the fob again and check that the battery is sitting flat and the positive side is facing up.

What to do if the fob still does not work

If the fob does not respond after you install a new battery, the problem is usually one of three things: the battery is installed upside down, the battery contacts are dirty, or the fob itself has a hardware problem.

Open the fob again and check the battery orientation. If it is correct, remove the battery and wipe both the battery and the metal contacts inside the fob with a clean, dry cloth. Dust or corrosion on the contacts can block the electrical connection. Reinstall the battery and test again.

If the fob still does not work after you have checked the battery twice, the problem is likely inside the fob itself — a broken button, damaged circuit board, or corroded contacts that cleaning cannot fix. At that point, you will need to contact your BMW dealer or a locksmith who makes BMW keys. A replacement fob costs between $200 and $400 depending on your model year.

Frequently Asked Questions

Where do I buy a CR2032 battery?

Any pharmacy, supermarket, or drugstore sells CR2032 batteries in the aisle with watch batteries, hearing aid batteries, and small electronics. Walmart, Target, CVS, Walgreens, and most grocery stores carry them. You can also order them online, but buying one in person means you can test your fob right away.

Can I use a different battery type if I cannot find CR2032?

No. CR2032 and CR2025 are not interchangeable with other battery types, and using the wrong size will not work. CR2032 and CR2025 are close in size but different in thickness. If your fob needs CR2032 and you use CR2025, the battery may not make proper contact. Stick with the correct type.

How often do I need to replace the battery?

Most BMW key fob batteries last three to four years with normal use. If you use your fob frequently — pressing buttons multiple times a day — the battery may wear out faster. If you notice the fob only works when you hold it close to the car, the battery is running low and needs replacement soon.

What if my fob has a touch button instead of physical buttons?

Newer BMW fobs with touch-sensitive buttons use the same battery replacement process, but the case may open differently. Look for a slot or seam and try the coin method first. If that does not work, check your owner's manual for your specific model year, as some newer designs have a small release button instead of a slot.