BMW key fob batteries typically last three to four years and cost $10 to $25 to replace

Your BMW key fob runs on a coin-cell battery — usually a CR2032, CR2025, or CR2016 depending on your model year and fob type. When the battery dies, the fob stops locking and unlocking your car from a distance, though you can still use the physical key blade inside. Replacing it takes about five minutes and requires no tools beyond a coin or flat object to pry open the fob case.

The battery itself is inexpensive and available at any pharmacy, grocery store, or hardware store. You do not need to visit a BMW dealership unless your fob has a deeper problem — like water damage or a broken circuit board — that a new battery will not fix.

Key Takeaways

  • BMW key fob batteries are standard coin cells (CR2032, CR2025, or CR2016) sold at drugstores and supermarkets for $5 to $15.
  • You can open most BMW fobs by sliding a coin into the seam on the edge and gently twisting to separate the two halves.
  • Note the orientation of the old battery before you remove it so you install the new one the same way — positive side up or down matters.
  • If the fob still does not work after a new battery, the problem is likely a broken button contact or water damage, not the battery itself.

Identifying which battery your fob needs

The easiest way to find out which battery fits your fob is to open it and look at the old battery. The battery type is printed on its face — you will see "CR2032" or similar. Write down that number before you go to the store, or take a photo of the battery itself.

If you want to know before opening the fob, you can search your BMW model year and "key fob battery" online, or call a BMW dealership parts department and give them your vehicle identification number (VIN). They will tell you the correct battery in under a minute. Most BMW fobs from 2000 onward use CR2032, which is the most common size.

How to open your BMW key fob

Look at the edge of your fob for a small seam or slot. On most BMW fobs, this runs along one of the long sides. Slide a coin — a dime or penny works well — into the seam and gently twist it like you are opening a paint can. Do not force it; the two halves should separate with light pressure.

Some newer BMW fobs have a small button or lever on the back that you press to release the battery cover. Check the back and sides of your fob first before you try the coin method. If you see a small rectangular button, press it and the cover should slide out.

Once the fob is open, you will see the battery sitting in a small plastic holder. Note which side is facing up — the positive (+) or negative (−) side. This matters when you put the new battery in.

Removing and replacing the battery

Gently lift the old battery out of its holder. If it is stuck, use your fingernail or the edge of the coin to nudge it up slightly. Do not pry hard or you risk damaging the plastic holder underneath.

Before you insert the new battery, check the orientation of the old one. If the positive side was facing up, the positive side of the new battery should also face up. Slide the new battery into the holder the same way the old one came out. It should sit flat and snug without forcing.

Close the fob by pressing the two halves together until you hear or feel a click. Test the lock and unlock buttons from a few feet away from your car. If the fob works, you are done. If it does not, open it again and check that the battery is sitting flat in its holder and oriented correctly.

Where to buy a replacement battery

Coin-cell batteries are sold at pharmacies (CVS, Walgreens), supermarkets (grocery stores usually have a pharmacy section), hardware stores (Home Depot, Lowe's), and online retailers (Amazon, eBay). A single battery costs between $5 and $15. Some stores sell them in multipacks for $10 to $20 if you want spares.

You do not need a special "BMW" battery — a CR2032 is a CR2032 regardless of the brand. Generic store brands work just as well as name brands like Energizer or Duracell. If you are unsure which size you need, buy a CR2032; it is by far the most common size for BMW fobs.

What to do if a new battery does not fix the problem

If you installed a fresh battery and the fob still does not work, the problem is not the battery. The most common causes are a worn-out button contact (the rubber pad inside the fob that presses the circuit board) or water damage inside the fob.

Button contacts can wear out after years of use and stop making electrical contact even when pressed. Water damage happens if the fob gets wet and the moisture corrodes the circuit board or battery contacts. Neither of these problems can be fixed at home. At this point, you have two options: buy a replacement fob from a BMW dealership or a third-party seller online, or have a locksmith reprogram a used fob to your car.

A new OEM (original equipment manufacturer) fob from a BMW dealership costs $200 to $500 depending on your model. Used fobs from online sellers cost $50 to $150 but require programming. A locksmith can program a fob for $100 to $200. Before you spend money on any of these, try the battery replacement first — it solves the problem about 90 percent of the time.

How to extend the life of your key fob battery

Coin-cell batteries last longest when kept dry and at room temperature. Avoid leaving your fob in hot cars, wet pockets, or direct sunlight for long periods. These conditions drain the battery faster and can cause corrosion inside the fob.

If you do not use your car often, remove the battery from the fob when you store it for more than a few weeks. This prevents the battery from slowly draining while the fob sits unused. When you are ready to use the car again, reinstall the battery and test the fob before you drive.

Frequently Asked Questions

Can I replace the battery myself or do I need a dealership?

You can replace it yourself in about five minutes with a coin and a new battery from any store. You do not need special tools or training. A dealership will do it for you, but you will pay a service fee ($50 to $100) for something that costs $10 and takes five minutes at home.

What if I put the battery in backwards?

The fob will not work if the battery is backwards, but it will not damage anything. straightforward open the fob again and flip the battery so the positive side faces the correct direction. Coin-cell batteries are designed to be safe even if installed incorrectly.

How do I know if my fob battery is actually dead?

Try the buttons from different distances — start close to the car and move farther away. A dying battery often works from a few feet away but not from across a parking lot. If the buttons do not work at any distance, the battery is likely dead. You can also try replacing the battery and seeing if that fixes it; if it does, the old battery was the problem.

Is there a difference between cheap and expensive coin-cell batteries?

Generic and name-brand coin-cell batteries perform similarly for key fobs. The main difference is shelf life — name brands like Energizer may hold a charge slightly longer if stored for years before use. For when ready use, a $5 generic battery works just as well as a $15 name brand.

What should I do with the old battery?

Coin-cell batteries contain small amounts of lithium and should not go in regular trash. Take the old battery to a pharmacy, hardware store, or recycling center — most accept used batteries for free. Some stores that sell batteries also take old ones back.