Most key fob batteries are user-replaceable and cost $3 to $10
You can replace your key fob battery yourself without tools or a trip to the dealership. The battery sits in a compartment inside the fob, held by a small clip or spring. The whole process takes about five minutes and costs less than a coffee.
The first step is finding out which battery your fob needs. Look for a small slot or seam running around the edge of the fob — this is where the two halves separate. Some fobs have a slot on the side; others have one along the back. Once you locate the seam, you can pry gently with a coin or flathead screwdriver to open it.
Inside, you will see a small round battery, usually silver-colored, with a number printed on top like CR2032 or CR2025. Write down that number or take a photo. That number tells you exactly which replacement battery to buy at any pharmacy, supermarket, or hardware store.
Key Takeaways
- Key fob batteries are labeled with a code (like CR2032) printed on the battery itself, and you can buy the exact replacement at any drugstore or supermarket.
- The fob opens by prying gently along the seam with a coin or flathead screwdriver, and the battery slides out or unclips in seconds.
- When you install the new battery, the positive side (marked with a + symbol) must face up or down depending on how the old one was oriented.
- If the fob still does not work after you replace the battery, the problem is usually a dirty contact or a broken button, not the new battery.
Opening the fob without breaking the plastic
The seam where the two halves meet is usually tight, and forcing it can crack the plastic. Use a coin — a dime or penny works well — and insert it into the slot at a shallow angle. Do not twist hard. Instead, rock the coin gently back and forth to work the halves apart.
If the fob has a slot on the side rather than the back, start at that slot and work your way around the edge. You will feel the halves begin to separate. Once there is a small gap, you can usually pry the rest open with your fingers.
Some newer fobs have a small button or latch on the back that you press to release the battery compartment. Check the back of your fob for a tiny button or arrow before you try prying.
Removing and replacing the battery
Once the fob is open, you will see the battery held in place by a metal clip or spring on one side. The battery is usually a flat, round disc about the size of a dime. Gently lift the edge of the clip or spring and slide the old battery out. Do not force it — it should come free with light pressure.
Before you install the new battery, look at how the old one was oriented. The battery has a flat side marked with a + symbol (positive) and a flat side marked with a − symbol (negative). The positive side must face the same direction as it did in the old battery. If you flip it, the fob will not work.
Slide the new battery in under the clip or spring, positive side facing the correct direction. You should hear or feel a small click as the clip holds it in place. Close the fob by pressing the two halves together until they snap. You may hear a click or feel them lock.
Testing the fob and troubleshooting if it does not work
Stand near your car and press a button on the fob. You should see the lights flash or hear the locks click. If nothing happens, open the fob again and check that the battery is oriented correctly — positive side facing the same direction as before. This is the most common reason a fob does not work after a battery change.
If the battery is oriented correctly but the fob still does not work, the metal contacts inside the fob may be dirty. These are the small metal strips that touch the battery. Wipe them gently with a dry cloth or a pencil eraser, then close the fob and test again.
If the fob still does not respond, the problem is likely not the battery. A button may be stuck or broken, or the circuit board inside may have failed. In that case, you will need a replacement fob from your car manufacturer or a locksmith.
Where to buy replacement batteries
Once you know the battery code (CR2032, CR2025, or whatever is printed on your old battery), you can buy a replacement almost anywhere. Pharmacies like CVS and Walgreens stock key fob batteries in their health and beauty section or near the checkout. Supermarkets carry them in the pharmacy or electronics aisle. Hardware stores like Home Depot and Lowe's have them in the electrical section.
Online retailers like Amazon also sell key fob batteries, usually in packs of two or more. A single battery costs $3 to $10 depending on where you buy it and whether you purchase one or a pack. Buying a pack is often cheaper per battery if you have multiple fobs or want spares on hand.
Do not buy batteries from your car dealership unless you have no other option. Dealership batteries cost two to three times more than retail prices for the exact same product.
How long a new battery lasts
A new key fob battery typically lasts three to four years with normal use. If you use your fob several times a day, it may last two to three years. If you use it rarely, it may last four to five years or longer.
You will notice the fob starting to fail before the battery is completely dead. The range will get shorter — you will have to stand closer to your car for the buttons to work. The lights may dim. When you see these signs, it is time to replace the battery.
Some people replace the battery once a year as routine maintenance, even if the fob still works. This prevents being locked out if the battery dies unexpectedly. If you do this, keep the old battery in a drawer as a backup in case you lose your fob and need to transfer the battery to a replacement.
Frequently Asked Questions
Can I use any battery that fits, or does it have to be the exact code?
Use the exact code printed on your old battery. Different codes have different voltages and sizes, and using the wrong one can damage the fob or cause it to malfunction. The code is printed right on the battery, so there is no guessing.
What if I drop the battery or lose it before I can install it?
Batteries are small and straightforward to lose. When you remove the old battery, set it on a paper towel or in a small container so you do not lose it. If you do lose it, you still have the code written down or in a photo, so you can buy a replacement. Keep the new battery in its packaging until you are ready to install it.
Is it dangerous to touch the battery with my bare hands?
No. Key fob batteries are safe to handle with bare hands. They carry a small electrical charge, but it is not strong enough to hurt you. Wash your hands after handling batteries if you prefer, but it is not necessary.
My fob works again after I replaced the battery, but it stopped working after a few weeks. What went wrong?
The battery may be defective, or the contacts inside the fob may have gotten dirty again. Open the fob and check that the battery is still oriented correctly and making good contact with the metal clips. Wipe the contacts with a dry cloth or eraser. If a new battery still does not work, the fob itself may be damaged.