Most car key batteries cost $3 to $8 and take five minutes to swap out yourself
You can replace a car key battery without a dealer visit or special tools. The battery sits inside your key fob — the remote that locks and unlocks your car — and dies like any other battery. Once it stops working, you buy a replacement battery (usually a coin cell like CR2032 or CR2025), pry open the key fob, remove the old battery, and snap in the new one. The whole job takes longer to find a flathead screwdriver than to do the work.
The hardest part is knowing which battery your key takes. Your owner's manual lists it, or you can open the fob and read the number stamped on the old battery. Once you have the right replacement, the process is the same for nearly every car key fob on the road.
Key Takeaways
- Car key batteries cost $3 to $8 at any pharmacy, grocery store, or hardware store, and you do not need to visit a dealership.
- The battery type is printed on your old battery or listed in your owner's manual — common types are CR2032, CR2025, and CR2016.
- You need only a flathead screwdriver or coin to pry open the key fob; no special tools are required.
- After inserting the new battery, test the key fob before you leave the store to confirm the battery works.
Find out what battery your key fob needs
Open your key fob to see the battery inside. Most fobs have a seam running around the edge where the two halves meet. Slide a flathead screwdriver or coin into the seam and gently twist to separate the halves. Do not force it — if the fob does not budge, you may be pushing in the wrong spot. Try the seam on the other side.
Once the fob is open, look at the battery. A number is stamped or printed on it — CR2032, CR2025, or CR2016 are the most common. Write down this number or take a photo. If the battery is corroded or you cannot read the number, check your owner's manual. Search the manual for "key fob battery" or "remote battery," and it will list the type.
If you do not have the manual, search online for your car's year, make, and model plus "key fob battery." Most results will tell you the type within the first paragraph.
Buy the replacement battery at a store near you
Coin cell batteries are sold at pharmacies, grocery stores, hardware stores, and big-box retailers. Walgreens, CVS, Walmart, Target, Home Depot, and Ace Hardware all stock them. The battery costs $3 to $8 depending on the brand and store. Name brands like Energizer and Duracell cost slightly more than store brands, but they perform the same way.
Buy the battery before you fully disassemble the key fob, so you can test it right away. Some batteries sit on the shelf for years and may not work. Testing in the store saves a trip back.
Remove the old battery and insert the new one
With the key fob open, note which side of the battery faces up. The side facing up is usually marked with a plus sign (+). The new battery must go in the same way. Gently pry out the old battery with your fingernail or the screwdriver tip. Do not scratch the inside of the fob.
Drop the new battery into the slot, plus side up, and press down gently until it clicks or sits flat. The battery should not require force to seat. If it does not fit, you may have the wrong battery type — double-check the number on the old battery.
Close the fob and test it before you leave
Snap the two halves of the key fob back together. Align the seam and press firmly until you hear or feel a click. The fob should close flush with no gaps.
Stand near your car and press the lock and unlock buttons. Your car should respond — the lights should flash or you should hear the locks engage. If nothing happens, the battery may be defective or installed backwards. Open the fob again, flip the battery so the plus side faces the other direction, and test again. If it still does not work, try a different battery from the store.
What to do if the fob still does not work after battery replacement
A dead battery fixes most key fob problems, but not all. If the fob still does not work after you install a fresh battery, the problem is usually a broken button contact, water damage, or a dead receiver in the car itself.
Test the fob one more time by pressing each button firmly. Sometimes a button contact is dirty or corroded and needs a gentle cleaning. If you see corrosion inside the fob — white, green, or blue powder on the battery contacts — use a cotton swab and a tiny drop of rubbing alcohol to clean the contacts, let them dry, and try again.
If the fob still does not work and you see no corrosion, the fob itself is likely broken and needs replacement. Your dealership can order a new fob and program it to your car. This costs $150 to $400 depending on your car's make and model. Some locksmiths also program key fobs for less than a dealership, so call around before you commit to dealer pricing.
How to avoid key fob battery problems in the future
Key fob batteries last two to four years with normal use. You can extend that lifespan by keeping the fob away from extreme heat, moisture, and direct sunlight. Do not leave it in a hot car, drop it in water, or expose it to humidity for long periods.
If you notice the fob is not responding as quickly as it used to — you have to press the button twice or stand closer to the car — the battery is weakening. Replace it before it dies completely. A dying battery is easier to replace than a fob that has failed entirely.
Frequently Asked Questions
Can I use any CR2032 battery, or does the brand matter?
Any CR2032 works in your key fob. Name brands like Energizer last slightly longer than store brands, but the difference is small. Buy whichever is in stock and costs less. The battery type matters; the brand does not.
What if I lose the small battery while the fob is open?
Coin cell batteries are tiny and straightforward to lose. If you drop it, buy a new one — they cost $3 to $8. Do not try to reuse a battery that has been on the floor or in dirt. Keep the replacement battery in its package until you are ready to install it.
Is it safe to replace the battery myself, or should I go to a dealership?
It is safe to replace the battery yourself. The fob contains no dangerous parts, and the battery is not toxic. You cannot damage the car or the fob by opening it and swapping the battery. A dealership will charge $50 to $100 for the same five-minute job.
How do I know if my key fob battery is dead or if the fob is broken?
Replace the battery first. If the fob works after the new battery is installed, the old battery was dead. If it still does not work, the fob is broken. This test costs $3 to $8 and takes five minutes, so it is always worth trying before you assume the fob is damaged.
Can I replace the battery in a key fob that is glued shut?
Some newer fobs are glued instead of snapped together. If you cannot pry it open with a screwdriver, do not force it — you will crack the plastic. Take it to a dealership or locksmith. They have tools to open glued fobs without damage. The cost is usually $20 to $50 plus the battery price.