Most car key fob batteries cost $3 to $8 and take five minutes to swap out yourself
You can replace a car key fob battery without a mechanic or special tools. The battery inside a key fob typically lasts three to four years, and when it dies, the fob stops locking and unlocking your car from a distance. Opening the fob, removing the old battery, and installing a new one is a task most people can do at home with nothing but a coin or small flathead screwdriver.
The hardest part is knowing which battery type your fob uses. That information is printed on the battery itself once you open the fob, or you can find it in your car's owner manual. Once you have the right replacement battery, the job takes minutes.
Key Takeaways
- Key fob batteries cost between $3 and $8 at drugstores, supermarkets, or online retailers, and most cars use either CR2032 or CR2025 batteries.
- You can open most fobs with a coin or flathead screwdriver by prying along the seam where the two halves meet.
- The battery sits in a metal holder and slides out sideways; note which side faces up before you remove it so you install the new one the same way.
- If your fob has multiple buttons, the battery holder is usually under the circuit board, which you may need to lift out gently to access it.
- Test the fob before you close it completely by pressing a button and listening for the lock or unlock sound from your car.
Find out what battery your fob needs
Check your car's owner manual first. Look in the index under "key fob," "remote," or "battery," and the manual will list the battery type by model number. If you do not have the manual, search online for your car's year, make, and model plus "key fob battery type."
The most common types are CR2032 and CR2025. CR2032 is slightly thicker and is used in most modern cars. CR2025 is thinner and less common but still available at any drugstore. If you are unsure, you can open the fob and look at the battery itself—the model number is printed on top.
Buy the battery before you start. Drugstores like CVS and Walgreens stock both types in the watch and battery section. Supermarkets, dollar stores, and online retailers like Amazon also carry them. A single battery costs $3 to $8 depending on the brand and where you buy it.
Open the key fob
Look for a seam running around the edge of the fob where the two plastic halves meet. This seam is usually on the side or back. Slide a coin (a dime or penny works) or a small flathead screwdriver into the seam and gently twist to pry the two halves apart. Do not force it—if it does not budge, try a different spot along the seam.
Once you have a small gap, you can often use your fingernail or the coin to work your way around the edge and separate the halves completely. Some fobs have a small notch or indent designed as a pry point; if you see one, start there.
Set one half aside carefully. The circuit board and battery holder are usually attached to one half, and you want to avoid dropping or bending anything inside.
Remove the old battery and note its position
The battery sits in a metal holder that looks like a small cup or clip. Before you touch it, look at which side is facing up—the side with the + symbol or the flat side. This matters because you must install the new battery the same way.
Slide the battery out sideways or lift it straight up, depending on how the holder is designed. Most holders have a slight lip or clip on one end that you can use to pry the battery out gently. If it is stuck, try sliding a coin edge under it to lift it.
Once the old battery is out, you can throw it away. Do not leave it sitting around—batteries can leak if they are damaged.
Install the new battery
Slide or place the new battery into the holder with the same side facing up as the old one was. If the + symbol was facing up before, the + symbol on the new battery should face up now. If you reversed it, the fob will not work.
Push the battery down or slide it in until it clicks or sits flush in the holder. You should feel a small click or resistance when it is seated correctly. Do not force it—if it does not fit smoothly, check that you have the right battery type and that it is oriented correctly.
Close the fob and test it
Before you snap the two halves back together, press one of the buttons on the circuit board and listen. You should hear a faint beep or click from the fob itself. This tells you the battery is making contact and the circuit is working.
If you hear nothing, the battery may be installed backwards or the fob may need a different battery type. Open it again and check the orientation and the battery model number.
Once you hear the beep, align the two halves and press them together until they click. The seam should be flush all the way around. Test the fob by standing near your car and pressing the lock and unlock buttons. You should hear your car lock or unlock and see the lights flash. If it works, you are done.
What to do if the fob still does not work
If the fob does not respond after you install a new battery, the battery may be the wrong type. Check the model number on the battery you installed against your owner manual or a search result for your car's year and make. If it is wrong, buy the correct type and swap it out.
If the battery type is correct and the fob still does not work, the circuit board or buttons inside the fob may be damaged. Water damage, a cracked circuit board, or worn button contacts can prevent the fob from working even with a fresh battery. In that case, you will need a replacement fob from your car's dealer or an aftermarket fob from an electronics retailer.
A replacement fob typically costs $50 to $200 depending on your car's make and model. Some dealers charge extra to program the fob to your car, though many newer cars can program a new fob yourself by turning the key in the ignition a certain number of times—check your owner manual for the steps.
Frequently Asked Questions
Can I use a different battery type if I cannot find the right one?
No. CR2032 and CR2025 are not interchangeable—they have different thicknesses and voltages. Using the wrong type can damage the circuit board or cause the fob to malfunction. Buy the correct type before you open the fob.
How long does a new key fob battery last?
Most key fob batteries last three to four years with normal use. Heavy use—pressing the buttons many times a day—can shorten the lifespan to two years. When the battery starts to die, the fob will work only from shorter distances before it stops responding entirely.
Do I need to reprogram my fob after changing the battery?
No. Changing the battery does not erase the fob's programming. Once you install the new battery and close the fob, it should work when ready without any additional steps.
What if I drop the battery or the circuit board while the fob is open?
If you drop the battery, pick it up and inspect it for cracks or dents. A small dent usually does not matter, but a cracked battery can leak and damage the fob. If you drop the circuit board, check that no components are bent or loose. If everything looks intact, reassemble the fob and test it. If something is visibly broken, you will need a replacement fob.
Can I buy a universal key fob instead of replacing the battery?
Universal fobs exist, but they are not true replacements—they work with many car models but not all, and they cost $20 to $50. Before buying one, check that it is compatible with your specific car year and make. If your original fob's battery replacement does not work, a universal fob may be worth trying, but a dealer replacement fob is more reliable.