Most key fob batteries cost $3 to $8 and last three to four years
A dead key fob battery is one of the easiest car problems to fix yourself. You do not need tools, a mechanic, or special knowledge — just the right battery type and two minutes. The battery itself costs between $3 and $8 at any pharmacy, supermarket, or hardware store. The whole job takes longer to find your key fob than to change it.
The hardest part is knowing which battery your fob needs. Most car key fobs use a coin-cell battery — a flat, round battery about the size of a dime. The most common types are CR2032, CR2025, and CR2016. Your owner's manual will tell you which one, or you can take your fob to any pharmacy and they will identify it for you in seconds.
Key Takeaways
- Identify your battery type by checking your owner's manual, the fob itself, or asking at a pharmacy — the most common types are CR2032, CR2025, and CR2016.
- Most key fobs open by prying a thin slot with a coin or flathead screwdriver, though some have a button or slide mechanism on the side.
- Note which side of the battery faces outward before you remove it, because the new battery must go in the same way.
- If your fob still does not work after the battery change, the problem is likely a worn contact or water damage, not the battery itself.
Finding the seam and opening your fob
Most key fobs have a thin seam running around the edge where the two plastic halves meet. This seam is where you pry the fob open. Look for a small slot or notch — some fobs have a visible line, others have a tiny indentation you have to feel for. A coin works best for this step, though a flathead screwdriver or a butter knife will also work.
Insert your coin into the seam and twist gently. Do not force it — the fob should pop open with light pressure. If it does not budge, you may have the wrong seam. Some fobs have a button or slide on the side instead of a seam. Check the edges and back of your fob for any button or lever before you try prying.
Once the fob opens, you will see the battery sitting in a small metal holder. The holder usually has two metal tabs or springs that hold the battery in place. Do not lose these tabs — they are what keeps the new battery from falling out.
Removing the old battery and noting its position
Before you touch the old battery, look at which side is facing up. The side facing you is usually marked with a + or − symbol. This matters because the new battery must go in the same way. If you put it in backwards, the fob will not work.
Gently pry the battery out using your coin or screwdriver. It should come free easily. If it is stuck, you may need to lift one of the metal tabs slightly to release it. Once it is out, set it aside — you do not need to keep it, but it is good to have it nearby so you can check the battery type if you are unsure.
Installing the new battery
Take your new battery and hold it so the same side that was facing up on the old battery is facing up on the new one. Slide the new battery into the holder, making sure the metal tabs grip it on both sides. You should hear or feel a small click when it seats properly.
Do not force the battery in. If it does not slide in smoothly, you may have it backwards or the wrong size. Check the battery type on the package and make sure it matches what came out of your fob.
Closing the fob and testing it
Press the two halves of the fob back together. You should hear a click when they snap into place. The seam should be flush — if there is a gap, the fob is not fully closed and may not work properly. Press harder until you hear the click.
Test the fob by pressing each button while standing near your car. You should see the lights blink or hear the locks click. If nothing happens, open the fob again and check that the battery is seated correctly and facing the right direction. If the fob still does not work after you have checked the battery twice, the problem is likely a worn contact inside the fob or water damage, not the battery.
What to do if the fob still does not work
If you have installed a fresh battery and the fob still does not respond, the issue is usually inside the fob itself. Water damage is common — if your fob has ever been dropped in water or exposed to heavy moisture, the metal contacts inside may be corroded. You can try opening the fob and gently cleaning the metal contacts with a dry cloth, but this does not always work.
A worn contact or a broken button can also cause the fob to stop working even with a new battery. In these cases, you will need a replacement fob. Your car dealership can order one, though the cost is usually $200 to $500 depending on your car model. Some aftermarket fobs are cheaper but may not work with all vehicles.
Where to buy a replacement battery
You can buy a key fob battery at any pharmacy, supermarket, drugstore, or hardware store. Walgreens, CVS, Walmart, Target, and Home Depot all stock coin-cell batteries. You can also order them online from Amazon or eBay for the same price. Buy a pack of two or three — they are inexpensive and last a long time if stored in a cool, dry place.
If you are not sure which battery type you need, bring your fob with you to the store and ask an employee to identify it. This takes 30 seconds and saves you from buying the wrong size.
Frequently Asked Questions
Can I use any CR2032 battery or does it have to be a specific brand?
Any CR2032 battery will work — the brand does not matter. Duracell, Energizer, and store brands all perform the same. The important thing is the battery type, not the brand.
What if I cannot get the fob open?
Try a different tool — a coin works for most fobs, but some respond better to a flathead screwdriver or a plastic spoon. If you still cannot open it, check your owner's manual for instructions specific to your car model. Some fobs have a hidden button or release mechanism you need to press first.
How long does a key fob battery last?
Most key fob batteries last three to four years with normal use. If you use your fob frequently, the battery may wear out faster. If you rarely use it, it may last longer. A battery that dies suddenly after only a few months usually means the fob has water damage or a worn contact.
Is it safe to replace the battery myself or should I go to a dealership?
It is completely safe to replace the battery yourself — there is no risk of damage to the fob or your car. A dealership will charge you $50 to $100 for the same five-minute job. Doing it yourself saves money and takes less time.
What should I do with the old battery?
Coin-cell batteries can be recycled at most pharmacies and electronics stores. Many places have a battery recycling bin near the checkout. You can also throw it in the trash — coin-cell batteries are not considered hazardous waste in most places, though recycling is better for the environment.