BMW key batteries wear out like any other battery, and replacing one takes about five minutes and costs between $5 and $15 for the battery itself

Most BMW key fobs use a coin-cell battery — usually a CR2032, CR2025, or CR2016 — that you can buy at any pharmacy, grocery store, or hardware store. The battery sits inside the fob's plastic case, and you do not need special tools or a dealer visit to swap it out. You will need to open the fob, identify which battery type yours uses, buy the replacement, and snap it back in place.

The whole process takes longer to read about than to do. The hardest part is usually opening the fob without breaking the plastic clips that hold it together.

Key Takeaways

  • BMW key fobs use a replaceable coin-cell battery, most commonly CR2032, that you can buy at any drugstore for $5 to $15.
  • You open the fob by sliding a flat tool into the seam between the two plastic halves and gently prying them apart.
  • The battery sits in a metal holder inside the fob; note which side faces up before you remove it, then install the new one the same way.
  • If the fob still does not work after you replace the battery, the problem is likely a worn contact or a dead fob circuit, not the battery.

Identify your BMW key battery type before you buy

Open your fob first so you can see the battery itself. The battery type is printed on the metal disc — you will see something like "CR2032" or "CR2025" stamped into it. Write down the number or take a photo with your phone so you have it when you walk into the store.

If you cannot open the fob or the battery marking is worn away, BMW key fobs in most models from 2000 onward use CR2032 as the standard. Older fobs and some specialty models use CR2025 or CR2016, but CR2032 is the safe default. If you buy the wrong size, you will know when ready when you try to fit it in the holder — it will be too loose or too tight.

Open the fob without breaking the plastic clips

Look at the seam that runs around the edge of your fob where the two plastic halves meet. You will see a small slot or gap in this seam, usually on one of the long sides. This is where you insert a flat tool to pry the halves apart.

Use a flathead screwdriver, a butter knife, or a plastic pry tool — anything flat and thin. Slide it into the seam and gently rock it back and forth to separate the halves. Do not force it or you will crack the plastic. Once you feel the halves start to give, work your way around the edge, lifting a little at a time, until the two pieces come apart. The battery holder will be visible inside one half.

Remove the old battery and note its position

The battery sits in a metal holder that has two small metal contacts — one on each side. Before you touch anything, look at which side of the battery faces up. The side marked with a + or a flat surface is the positive side; the other side is negative. You need to install the new battery the same way.

Gently pry the battery out of the holder using your fingernail or the edge of your flat tool. If it is stuck, a tiny dab of pressure on one edge will pop it out. Do not force it or you may bend the metal contacts inside the holder.

Install the new battery and close the fob

Place the new battery into the holder with the same side facing up as the old one. It should sit flat and snug in the metal holder. If it is loose or does not sit flat, you have the wrong battery size — take it back and exchange it for the correct type.

Now close the fob by pressing the two plastic halves together. Start at the seam where you pried it open and work your way around the edge, pressing firmly until you hear or feel a click. The halves should fit flush with no gaps. Test the fob by pressing each button — the lights should come on and the car should respond to the lock and unlock buttons.

What to do if the fob still does not work

A new battery fixes the problem about 90 percent of the time. If your fob still does not work after you install a fresh battery, the issue is usually one of three things: the battery contacts inside the holder are corroded or worn, the circuit board inside the fob is dead, or the receiver in your car has stopped responding to that fob.

If the contacts look dark or crusty, clean them gently with a pencil eraser or a cotton swab dipped in rubbing alcohol, let them dry, and try again. If the fob still does not work and your spare fob does work, the problem is the fob itself and you will need a replacement from BMW or a locksmith. If both fobs stop working at the same time, the receiver in your car may need service, and you should contact a BMW dealer.

Where to buy a replacement battery

You can buy a CR2032, CR2025, or CR2016 battery at any of these places: a pharmacy or drugstore (CVS, Walgreens, Rite Aid), a grocery store (most have a battery section), a hardware store (Home Depot, Lowe's, Ace), a big-box retailer (Target, Walmart), or online (Amazon). Prices are nearly identical everywhere — usually $3 to $8 for a single battery or $8 to $15 for a pack of two or four.

Do not buy batteries from a BMW dealer unless you have no other option. Dealer batteries cost two to three times more than retail batteries and are the same product.

Frequently Asked Questions

How often do BMW key batteries need to be replaced?

Most coin-cell batteries last three to four years with normal use. If you use your fob frequently — pressing the buttons many times a day — the battery may wear out in two to three years. You will notice the buttons becoming less responsive or the range shortening before the battery dies completely.

Can I use a different battery type if I cannot find the exact one?

Not safely. CR2032, CR2025, and CR2016 are different sizes and voltages. Using the wrong type can damage the contacts inside the fob or cause the buttons to malfunction. Stick with the type printed on your old battery. If you cannot find it, call a BMW dealer or locksmith and they will tell you which type your model uses.

What if I lose the fob while it is open?

If you lose the battery, you can buy a replacement at any store. If you lose or break the plastic fob case, you will need to order a new fob from BMW or a locksmith. The fob case itself costs $50 to $150 depending on your BMW model.

Do I need to reprogram the fob after I replace the battery?

No. Replacing the battery does not erase any programming. The fob will work exactly as it did before once you install the new battery. You only need to reprogram a fob if you have replaced the circuit board or if the fob was previously erased.

Is it safe to replace the battery myself, or should I go to a dealer?

It is completely safe to replace the battery yourself. You are only handling a small battery and plastic pieces — there is no risk of electrical shock or damage to your car. A dealer will charge you $50 to $100 for the same five-minute job, so doing it yourself saves money and time.