Most key fob batteries come out by popping the case open and swapping in a new coin cell
A dead key fob battery is one of the easiest car fixes you can do yourself. The whole job takes about five minutes and costs between $3 and $10 for the replacement battery. You do not need tools for most fobs — just your fingernail or a coin to pry the case apart, then slide out the old battery and drop in a new one that matches the original.
The hardest part is finding out which battery type your fob uses. That information is printed on the battery itself once you open the case, or you can check your owner's manual. Most common fobs use CR2032, CR2025, or CR2016 batteries — all coin-shaped and sold at any pharmacy, grocery store, or hardware store.
Key Takeaways
- Most key fob batteries are coin cells (CR2032, CR2025, or CR2016) that cost $3 to $10 and are sold at drugstores and supermarkets.
- You can open the fob case with your fingernail or a coin — no screwdriver needed for most models.
- The battery type is printed on the old battery itself, so open the fob first if you do not know which one you need.
- Pay attention to which side of the battery faces outward when you remove it, because the new one must go in 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.
Find out what battery type your fob uses
Open your owner's manual and search for "key fob battery" or "remote battery." Most manuals list the exact battery type in a table or in the fob section. If you do not have the manual, you can find it online by searching "[your car year and model] owner's manual PDF."
If you cannot find the manual, open the fob case first (see the next section) and look at the old battery. The type is stamped on top — it will say something like CR2032 or CR2025. Write that number down and take a photo so you have it when you go to the store.
Open the fob case without breaking it
Look for a small slot or seam running around the edge of the fob. This is where the two halves of the plastic case meet. Slide your fingernail or a flat coin (a dime works well) into the seam and gently twist to pop the case apart. Do not force it — if it does not budge, try a different spot along the seam.
Some fobs have a small button or latch on the back that you press to release the battery cover. Check the back and sides before you try prying. Once the case is open, you will see the battery sitting in a small metal holder, usually held in place by a spring or just resting in a slot.
Remove the old battery and note its position
Before you touch the battery, look at which side is facing up. The side with the + symbol (the positive side) should be facing either up or down — this matters. Take a quick photo or write down "positive side up" or "positive side down" so you remember when you install the new one.
Gently pry the battery out of its holder using your fingernail or the edge of a coin. If it is held by a spring, the spring may push the battery out — be ready to catch it so it does not roll across the floor. Set the old battery aside.
Insert the new battery the same way the old one faced
Take your new battery and place it in the holder with the positive side facing the same direction as the old battery did. If the positive side was facing up, the positive side of the new battery should face up. Press gently until you hear or feel a small click — the battery should sit flat in the holder.
Do not force the battery down. If it does not sit flush, you may have it upside down. Flip it and try again. Once it is seated, close the fob case by pressing the two halves together until they snap. You should hear a click.
Test the fob before you leave the store
Stand near your car and press each button on the fob — lock, unlock, trunk, panic, or whatever buttons yours has. You should see the car lights flash or hear the locks click. If nothing happens, open the fob again and check that the battery is seated all the way down and facing the right direction.
If the fob still does not work after you reseat the battery, the problem is not the battery. The metal contacts inside the fob may be corroded, or the fob circuit itself may be dead. In that case, you will need a replacement fob from your car dealer or a locksmith.
Where to buy the replacement battery
Coin cell batteries are sold at drugstores (CVS, Walgreens), supermarkets (most have a pharmacy section), hardware stores (Home Depot, Lowe's), and online (Amazon, eBay). A single battery costs $3 to $10 depending on the brand. Name brands like Duracell and Energizer cost more than store brands, but they all work the same way.
Buy one extra battery while you are there. Key fob batteries last three to four years, so having a spare on hand means you will not have to make another trip when the next one dies. Store it in a cool, dry place — not in a hot car or a damp bathroom.
Frequently Asked Questions
Can I use any CR2032 battery, or does it have to be a specific brand?
Any CR2032 works — the number tells you the size and voltage, not the brand. Duracell, Energizer, and store brands are all the same inside. Buy whatever is cheapest.
What if I put the battery in backwards?
The fob will not work, but you will not damage anything. Open it back up, flip the battery, and close it again. The positive side (marked with a +) must face the same direction as the old battery did.
How long does a key fob battery last?
Most coin cell batteries last three to four years in a key fob. If you use the fob heavily — pressing buttons many times a day — it may die sooner. Cold weather can also drain batteries faster.
Is it normal for the fob to stop working right after I replace the battery?
No. If a new battery does not work, the battery is probably not seated all the way down, or it is upside down. Open the fob again and check that the battery is flat in the holder and facing the right direction. If it still does not work, the fob circuit may be dead.
Can I clean the battery contacts to make the fob work better?
Yes. If the fob is weak or spotty, open it and wipe the metal contacts inside with a dry cloth or a pencil eraser. Corrosion on the contacts can block the battery from making good contact. Let it dry completely before you close the fob.