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. The battery itself costs between $3 and $10, and you do not need any tools beyond what you probably have in a junk drawer. The whole job takes about five minutes once you know where the battery sits and which direction it goes in.
The hardest part is usually opening the fob without breaking the plastic case. Most fobs split along a seam, and a flathead screwdriver or coin works to pry them apart. Once it is open, the battery slides or clicks out, you note which side faces up, and you slide the new one in the same way.
Key Takeaways
- Key fob batteries are coin-cell batteries, usually CR2032, CR2025, or CR2016, and cost $3 to $10 at any pharmacy, grocery store, or hardware store.
- Most fobs split along a seam with a flathead screwdriver or coin; look for a small slot or line running around the edge before you force anything.
- Note which side of the battery faces up before you remove it, because the new battery must go in the same way or the fob will not work.
- If the fob still does not work after you replace the battery, the problem is likely a corroded contact or a broken button, not the battery itself.
Identify your fob's battery type before you buy
Key fob batteries are small coin-cell batteries, and the most common types are CR2032, CR2025, and CR2016. The numbers tell you the size: CR2032 is 20 millimeters across and 3.2 millimeters thick, while CR2025 is the same width but slightly thinner. Most car fobs use CR2032, but some older or smaller fobs use CR2025 or CR2016.
The easiest way to find out which one you need is to open the fob and look at the battery itself. The type is printed on the metal top. If you cannot open it yet, check your owner's manual or search online for your car's year, make, and model plus "key fob battery." Once you know the type, you can buy a replacement at a pharmacy, grocery store, hardware store, or online. Most places sell them in packs of two or four for $5 to $10.
Open the fob without cracking the plastic
Most key fobs have a seam running around the edge where the two halves of the plastic case meet. Look for a thin line or slot, usually on one of the long sides. Slide a flathead screwdriver or a coin into that slot and gently twist to pry the two halves apart. Do not force it—if you meet hard resistance, you may be pushing in the wrong spot.
Some fobs have a small button or lever on the back that you press to release the battery cover, rather than a seam to pry. Check the back and sides before you reach for a screwdriver. If your fob has a screw holding the case together, you will need a small Phillips or flathead screwdriver to remove it. Once the case is open, set the small metal spring or contact piece aside somewhere safe so you do not lose it.
Remove the old battery and note its position
The battery sits in a small slot or holder inside the fob. Before you touch it, look at which side faces up—the side with the printed numbers and symbols should face either toward you or away from you, depending on your fob's design. Take a mental note or a quick photo so you remember the orientation.
Slide or pop the battery out of its holder. If it is stuck, a gentle pry with a plastic spoon or the edge of a coin usually works. Do not use a sharp metal tool that could scratch the inside of the fob or damage the contacts. Once the old battery is out, set it aside—you do not need to recycle it right away, but do not leave it where a child or pet could swallow it.
Insert the new battery in the same direction
Slide the new battery into the holder with the same side facing up as the old one. The battery should sit flat and click or snap into place. If it feels loose or does not sit flush, you may have it upside down—flip it and try again. The correct orientation is important: if the battery is backwards, the fob will not work.
Once the battery is in, press the two halves of the case back together until they snap. If your fob had a screw, replace it now. Test the fob by pressing each button and listening for the click or feeling for the vibration that tells you the battery is making contact. If nothing happens, open the fob again and check that the battery is facing the right way.
What to do if the fob still does not work
If you replaced the battery and the fob still does not respond, the problem is usually not the battery. The most common culprit is corrosion on the metal contacts inside the fob. If you see a white, green, or blue crusty coating on the metal contacts or the battery itself, that is corrosion. You can clean it off with a pencil eraser or a cotton swab dipped in rubbing alcohol. Rub gently until the metal is shiny again, let it dry, and test the fob.
If the fob still does not work after cleaning, one of the buttons or the circuit board inside may be broken. This is not something you can fix at home, and a replacement fob from a car dealership or a locksmith usually costs $150 to $400 depending on your car. Some dealerships will program a fob you buy elsewhere for a smaller fee. Before you spend that money, try the fob in different locations—sometimes a weak fob will work close to the car but not from across a parking lot, which is a sign the battery was actually the problem and you may have installed it backwards.
Frequently Asked Questions
Can I use a different battery type if I cannot find the exact one?
No. CR2032, CR2025, and CR2016 are different sizes and voltages, and using the wrong one can damage the fob's circuit board or not work at all. Stick with the type printed on your old battery or listed in your owner's manual. Any pharmacy or grocery store carries all three types.
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 many times a day, it may last two to three years. If you use it rarely, it may last five years or longer. There is no way to predict exactly when it will die, so keep a spare battery in your car or at home.
Do I need to reprogram my fob after I replace the battery?
No. The battery replacement does not erase any programming. Once you install the new battery, the fob should work when ready without any reprogramming. If it does not, the problem is likely the battery orientation or corrosion on the contacts, not the programming.
What should I do with the old battery?
Coin-cell batteries can be recycled at most pharmacies, electronics stores, and hazardous waste collection sites. Many places take them for free. Do not throw them in the trash where they could end up in a landfill or be swallowed by an animal.