Most key fob batteries come out by sliding or prying the case open
The battery in your key fob is a small coin-shaped cell, usually a CR2032 or CR2025, that you can buy at any drugstore for a few dollars. Getting it out takes no tools beyond maybe a coin or a flathead screwdriver, and the whole job takes about five minutes. The hard part is not the battery swap itself—it's knowing which direction your particular fob opens.
Start by looking at the seam that runs around the edge of your fob. Most fobs split into two halves along that seam. Some slide apart (one half slides toward the key ring), some pry open like a clamshell, and a few have a small screw you remove first. Your owner's manual will show you which, but if you do not have it, a quick search for your car's year, make, and model plus "key fob battery replacement" will show you the exact motion.
Key Takeaways
- Most key fob batteries are CR2032 or CR2025 coin cells that cost $3 to $8 and are sold at pharmacies, grocery stores, and hardware stores.
- The fob case opens by sliding, prying, or unscrewing—check your owner's manual or search your car's year and model to see which applies to yours.
- Note which side of the battery faces outward before you remove it, because the new battery must go in the same way.
- If the fob still does not work after you swap the battery, the problem is likely a worn contact or a dead circuit board, not the battery itself.
Identify your battery type before you buy a replacement
The battery type is printed on the old battery itself. When you open the fob, look at the flat disc sitting in the case—it will have a number stamped on it like CR2032, CR2025, or CR2016. Write that number down or take a photo, because you need the exact match when you buy the new one.
If you cannot read the old battery clearly, the CR2032 is the most common type in car key fobs and is a safe bet. It is thicker and holds more charge than the CR2025, so if you are unsure, the CR2032 will work in most fobs that use either one. The battery cost is the same either way.
Open the fob without breaking the plastic clips
The two halves of your fob are held together by small plastic clips or hinges. When you pry or slide the case open, go slowly and watch for resistance—if you feel the case fighting you, you are probably going the wrong direction.
If your fob slides apart, grip one half firmly and slide the other half toward the key ring with steady, even pressure. If it pries open, use a coin edge or a flathead screwdriver in the seam and gently rock it back and forth rather than jamming it in hard. The clips are fragile, and a broken clip means the fob will not close properly even after you put the battery in.
Remove the old battery and note its orientation
Once the case is open, you will see the battery sitting in a small metal holder or slot. Before you touch it, look at which side is facing up—the side with the + symbol or the side with no marking. This matters, because the new battery must go in the same way.
Gently pry the old battery out with your fingernail or the edge of a coin. If it is stuck, a tiny dab of rubbing alcohol around the edge can help it slide out. Do not force it, because you can damage the metal contacts inside the fob if you bend them.
Insert the new battery in the same orientation as the old one
Slide the new battery into the slot with the same side facing up as the old one was. It should sit flat and snug in the holder. If it rocks or feels loose, you may have it upside down—flip it and try again.
Once the battery is seated, close the fob by reversing the motion you used to open it. If it slides, slide it back. If it pries, press the halves together until you hear or feel the clips snap. Test the fob by pressing each button—the lights should come on and the car should lock and unlock.
What to do if the fob still does not work after the battery swap
If the buttons do nothing after you put in a fresh battery, the problem is not the battery. The metal contacts inside the fob may be corroded or worn, or the circuit board may have failed. Corrosion looks like a white or green film on the metal contacts inside the case.
If you see corrosion, try cleaning the contacts with a pencil eraser or a cotton swab dipped in rubbing alcohol. Let them dry completely before you close the fob and test it again. If there is no corrosion and the fob still does not work, the circuit board has likely failed, and the fob will need to be replaced. Your car dealer can order a new one, or you can buy an aftermarket fob online—both will need to be programmed to your car, which usually costs $50 to $200 at a dealer.
Where to buy the right battery
CR2032 and CR2025 batteries are sold at pharmacies (CVS, Walgreens), grocery stores, hardware stores (Home Depot, Lowe's), and online retailers. A single battery costs $3 to $8 depending on the brand. Name brands like Energizer and Duracell are reliable, but store brands work just as well and cost less.
Buy one extra battery while you are at it. Key fob batteries last three to four years, and having a spare on hand means you will not have to make another trip to the store when this one dies.
Frequently Asked Questions
Can I use a different battery type if I cannot find the exact one?
No. A CR2032 and a CR2025 look almost identical but have different thicknesses, and using the wrong one can prevent the fob from closing properly or cause the battery to make poor contact. Always match the number on the old battery exactly. If your store is out of stock, order online rather than substituting.
What if I put the battery in backwards?
The fob will not work, but the battery will not be damaged. Open the fob again and flip the battery over so the + symbol faces the same direction it did in the old battery. This is the most common mistake, and it is an straightforward fix.
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—pressing the buttons many times a day—it may last only two years. There is no way to extend the life, so plan on replacing it every few years.
Do I need to reprogram my key fob after changing the battery?
No. Changing the battery does not erase the fob's programming. As long as the fob worked before the battery died, it will work again once you put in a fresh battery. Reprogramming is only needed if you buy a new fob or if the fob was lost or stolen.
Is it safe to throw the old battery in the trash?
Check your local rules. Many communities have battery recycling programs because batteries contain materials that can harm the environment. Most drugstores and electronics retailers have a battery drop-off bin near the register. If your area has no program, throwing a single coin-cell battery in the trash is generally safe, but recycling is better.