Most key fob batteries take five minutes to swap out yourself
A dead key fob battery is one of the easiest car problems to fix at home. You do not need tools or special knowledge—just the right battery type and a way to open the fob case. The whole job takes about five minutes, and a replacement battery costs between $3 and $15.
The hardest part is usually figuring out which battery your fob needs. Car manufacturers use different sizes and types depending on the model year and fob design. Once you know the number, you can buy the battery at any pharmacy, supermarket, or hardware store.
Key Takeaways
- Find your fob's battery type by checking the owner's manual, looking inside the fob case itself, or calling your car dealership with your vehicle identification number (VIN).
- Common car key fob batteries are CR2032, CR2025, and CR2016—the numbers tell you the size and chemistry, and they are not interchangeable.
- Open the fob by prying along the seam with a coin, flathead screwdriver, or plastic pry tool; most fobs split into two halves rather than having a removable back.
- Note which side of the battery faces up before you remove it, then install the new one the same way and snap the case closed.
- If the fob still does not work after a new battery, the problem is usually a corroded contact or a broken circuit board, not the battery itself.
Find out what battery type your fob uses
The battery type is printed on the fob itself if you can open it, but you may not want to open it blind. Your owner's manual lists the battery type in the key fob section—search for "key fob battery" or "remote battery" in the index. If you do not have the manual, you can read it free from the manufacturer's website using your vehicle identification number (VIN), which is on your registration or dashboard.
If you do not want to search the manual, call your car dealership with your VIN and ask what battery the key fob takes. They will give you the answer in one call. You can also open the fob and look at the battery itself—the type is stamped on the top. Common types are CR2032, CR2025, and CR2016. Write down the exact number before you close it back up.
Buy the correct replacement battery
Once you know the type, buy the battery at a pharmacy, supermarket, or hardware store. Do not buy a generic "key fob battery" pack—buy the specific type your fob needs. CR2032, CR2025, and CR2016 are not interchangeable, even though they look similar. A battery that is too thick will not fit; one that is too thin will rattle and lose contact.
Batteries cost $3 to $15 depending on the brand. Name brands like Duracell and Energizer work fine, and store brands are usually identical. Some pharmacies will replace the battery for you while you wait for $5 to $10 if you do not want to do it yourself.
Open the fob case
Most key fobs split into two halves along a seam that runs around the edge. Look for a thin line where the two pieces meet. Slide a coin, flathead screwdriver, or plastic pry tool into the seam and twist gently to pop the case open. Start at one corner and work your way around if it does not pop on the first try. Do not force it—if you are meeting hard resistance, you may be prying in the wrong spot.
Some fobs have a removable back panel held by a small screw instead of a snap case. If you see a screw, use a screwdriver that fits it snugly—a screwdriver that is too small will strip the screw head. Set the screw somewhere you will not lose it.
Once the case is open, you will see the battery sitting in a plastic holder. It is usually a flat, round disc about the size of a dime. Note which side is facing up—the + symbol should be visible on top. This matters when you put the new battery in.
Remove the old battery and install the new one
Gently pry the old battery out of its holder with your fingernail or a plastic tool. Do not use a metal screwdriver—you can damage the circuit board. Once it is out, check the battery holder for corrosion. If the metal contacts are green or white, wipe them clean with a dry cloth or a pencil eraser.
Place the new battery into the holder with the + side facing up, the same way the old one was oriented. Press down gently until it clicks into place. If the battery sits loose or rattles, you may have the wrong size—double-check the type number.
Close the case and test the fob
Snap the two halves of the case back together, or screw the back panel on if your fob has a screw. You should hear or feel a click when the case closes. If it does not close flush, the battery may be installed upside down or the case may not be aligned—open it again and check.
Test the fob by pressing each button and watching your car. The locks should respond right away. If the fob still does not work, try pressing the buttons a few more times—sometimes a new battery needs a moment to make full contact. If it still does not work after 30 seconds, the problem is likely a corroded contact or a broken circuit board, not the battery.
When to replace the whole fob instead of just the battery
If a fresh battery does not bring the fob back to life, the circuit board or the buttons may be damaged. Water damage is common—if the fob has been dropped in water or sat in a humid environment, corrosion inside the case can break the electrical connections. A replacement fob costs $100 to $400 depending on the car, but some dealerships will program a used fob from a salvage yard for less.
Before you buy a new fob, try cleaning the battery contacts and the circuit board with a pencil eraser or a cotton swab dipped in rubbing alcohol. Let it dry completely before you reassemble it. This fixes the problem about half the time when corrosion is the culprit.
Frequently Asked Questions
Can I use a different battery type if it is close to the right size?
No. CR2032, CR2025, and CR2016 are not interchangeable. A battery that is too thick will not fit in the holder, and one that is too thin will lose contact and drain quickly. Always use the exact type your fob needs.
How long does a key fob battery last?
Most key fob batteries last three to four years with normal use. If you use the fob heavily or live in a humid climate, the battery may drain faster. There is no way to predict exactly when it will die—you will know when the buttons stop responding or respond slowly.
What if I lose the screw when I open the fob?
If your fob has a screw, put it somewhere safe before you open the case—a small dish or envelope works well. If you lose it, you can buy a replacement screw at a hardware store, but you will need to know the size. Most key fob screws are M1.4 or M2, very small. Your dealership can also sell you a replacement screw for a few dollars.
Does the fob need to be reprogrammed after I change the battery?
No. The battery change 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 reprogramming.
Why is my fob still not working after I put in a new battery?
The most common reason is corrosion on the battery contacts or circuit board. Open the fob again and clean the metal contacts with a pencil eraser or rubbing alcohol on a cotton swab. If that does not work, the circuit board may be damaged, and you will need a replacement fob.