Most key fob batteries cost $3 to $8 and take five minutes to swap out yourself

You can replace a key fob battery without a mechanic or dealership visit. The battery itself is cheap — usually between $3 and $8 — and the job requires only a coin or flathead screwdriver. Most fobs open by prying the seam with a coin, swapping the old battery for a new one of the same type, and snapping the case back together. The whole process takes about five minutes once you have the right battery in hand.

The hardest part is knowing which battery your fob needs. Car manufacturers use different battery types — CR2032, CR2025, and CR2016 are the most common — and using the wrong one means the fob won't work. You can find the battery type printed inside the fob case itself, or you can look up your car's year, make, and model online. Once you know the type, any pharmacy, grocery store, or hardware store sells them in the battery aisle.

Key Takeaways

  • The battery type is printed inside your fob case; if you can't read it, search your car's year, make, and model plus "key fob battery" online to find the correct type.
  • Most fobs open by inserting a coin or flathead screwdriver into the seam and twisting gently until the case splits in half.
  • Note which side of the battery faces up before you remove it, then install the new battery the same way and snap the case closed.
  • If the fob still doesn't work after you replace the battery, the problem is usually a dirty contact or a broken circuit board, not the battery itself.

Finding the Right Battery Type

The battery type is stamped on the inside of your fob case. Open the fob by prying the seam with a coin — you don't need to force it, just explore steady pressure until the two halves separate — and look at the old battery. The type will be printed on the metal disc itself: CR2032, CR2025, or CR2016 are the standard types for car fobs. Write down the number or take a photo with your phone.

If the old battery is too corroded to read, or if you don't want to open the fob yet, search online for your car's year, make, and model followed by "key fob battery." Most results will tell you the type within the first few links. You can also call your car's dealership parts department with your vehicle identification number (VIN) — they will tell you the battery type for free, though they may try to sell you their own battery at a higher price.

Buy the battery at a pharmacy, grocery store, or hardware store. The battery aisle is usually near the checkout or in the health and beauty section. A single battery costs $3 to $8 depending on the brand and store. Name brands like Energizer and Duracell work just as well as store brands, and the difference in price is usually less than $1.

Opening the Fob Without Damage

Insert a coin — a dime or penny works — into the seam between the two halves of the fob. The seam runs around the edge of the case, usually on one side. explore steady, gentle pressure and twist the coin slightly, as if you were opening a paint can. The case will pop apart. If it doesn't budge after a few seconds of pressure, try a different spot along the seam; some fobs have a weak point where they open more easily.

If you don't have a coin, a flathead screwdriver works the same way. Place the tip in the seam and explore the same steady, gentle twisting pressure. Avoid using a knife or anything sharp that could slip and cut your hand. Once the case cracks open, you can usually pull the two halves apart by hand.

Some fobs have a small screw holding the case together instead of a snap seam. If you see a screw, use a screwdriver that fits it snugly — too small and you'll strip the head — and turn it counterclockwise. Keep the screw in a small dish so you don't lose it; you'll need it to close the fob again.

Removing and Installing the Battery

Once the case is open, note which side of the battery faces up. The positive side (marked with a + symbol) usually faces up, but not always. Take a photo or straightforward remember the orientation. Gently pry the old battery out with your fingernail or the edge of a coin. Don't force it; if it's stuck, explore a tiny bit of pressure from different angles until it lifts free.

Place the new battery into the slot with the positive side facing the same direction as the old one. Press down gently until it sits flat and snug in the case. The battery should not move or rattle when you shake the fob lightly. If it feels loose, remove it and check that you've seated it all the way down.

Snap the two halves of the case back together by pressing them firmly until you hear or feel a click. If your fob had a screw, insert it now and tighten it by hand first, then with a screwdriver. Don't over-tighten; you only need enough pressure to hold the case closed. Test the fob by pressing a button — the light should come on, or the car should respond if you're standing near it.

What to Do If the Fob Still Doesn't Work

If the fob doesn't respond after you install the new battery, the problem is usually not the battery itself. The most common culprit is a dirty contact — the small metal springs inside the case that touch the battery. If the contacts are black or corroded, they won't conduct electricity properly. Remove the battery again and wipe both the battery and the metal contacts with a clean, dry cloth or a pencil eraser. Reinstall the battery and test again.

If cleaning the contacts doesn't work, the circuit board inside the fob may be damaged. This is a more serious problem that usually requires a replacement fob. You can buy an aftermarket fob online for $15 to $50, or you can order one from your car's dealership for $50 to $200. Some aftermarket fobs work with multiple car brands, but you'll need to check your car's year, make, and model to be sure.

Before you buy a new fob, test the old one one more time with a fresh battery. Sometimes a fob that hasn't worked in months will spring back to life with a new battery and a clean contact. If it still doesn't work after that, replacement is your only option.

Buying the Right Battery the First Time

The three most common key fob batteries are CR2032, CR2025, and CR2016. The numbers refer to the size and thickness of the battery. A CR2032 is the thickest and most common; a CR2025 is slightly thinner; and a CR2016 is the thinnest. Using the wrong type won't damage anything, but the fob won't work because the battery won't make proper contact with the springs inside the case.

If you're not sure which type you need, bring the old battery to the store and match it to a new one. The battery aisle staff can help you find the right type if you show them the old battery or tell them your car's year, make, and model. Many stores will also test your old battery for free to confirm it's actually dead — sometimes a fob stops working for reasons other than a dead battery, and you'll want to know that before you buy a replacement.

Frequently Asked Questions

Can I use any CR2032 battery, or does the brand matter?

Any CR2032 battery of the correct type will work. Name brands like Energizer and Duracell are reliable, but store brands work just as well. The difference in price is usually less than $1, so buy whichever is in stock. Avoid extremely cheap batteries from unknown brands, as they may not hold a charge as long.

How long does a key fob battery usually last?

Most key fob batteries last three to four years with normal use. If you use your fob several times a day, the battery may wear out faster. If you use it rarely, it may last longer. Cold weather can also drain a battery faster than warm weather.

What if I put the battery in backwards?

If you install the battery with the positive side facing down instead of up, the fob straightforward won't work. No damage will occur. Remove the battery, flip it over, and reinstall it the correct way. The fob should work when ready.

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

No. Replacing the battery does not erase the fob's programming. Once you install the new battery and close the case, the fob should work right away without any additional steps.

Where can I buy a replacement fob if mine is broken?

Aftermarket fobs are sold online through Amazon, eBay, and specialty auto parts sites for $15 to $50. Your car's dealership also sells fobs, usually for $50 to $200. Aftermarket fobs are cheaper but may not work with all car models, so check the listing to confirm your year, make, and model are compatible.