Most key fob batteries take five minutes to replace at home
You can change your key fob battery yourself without tools or a trip to the dealer. The battery sits in a small compartment inside the fob, and swapping it out takes about five minutes once you know where to look. The hardest part is usually opening the fob itself—most use a small slot or seam you pry open with a coin or flathead screwdriver.
The battery type depends on your car's make and model, but the most common are CR2032, CR2025, and CR2016 coins cells. You can buy replacements at any pharmacy, grocery store, or hardware store for two to five dollars. Knowing your fob's battery type before you start saves a trip back to the store.
Key Takeaways
- Check your owner's manual or the inside of your fob to find the exact battery type before you buy a replacement.
- Most fobs open by prying along a seam with a coin or flathead screwdriver—look for a small slot or line running around the edge.
- Note which side of the battery faces outward before you remove it, because the new one must go in the same way.
- Test the fob before you close it completely to make sure the new battery is making contact.
Find your fob's battery type
The battery type is printed on the inside of your fob or listed in your owner's manual. Open your fob if you can, or search online for "[your car year, make, model] key fob battery" to find the part number. Write down the type—CR2032 is by far the most common, but some fobs use CR2025 or CR2016.
Buy the replacement before you start. Coin cell batteries cost two to five dollars at pharmacies, supermarkets, dollar stores, and hardware stores. Do not buy the cheapest option if you can help it; a name-brand battery like Energizer or Duracell will last longer and make better contact inside the fob.
Open the fob without breaking the case
Look for a seam or slot running around the edge of your fob. Most fobs split in half along this line. Slide a coin—a dime or penny works well—into the slot and twist gently to pry the two halves apart. If your fob has a small slot rather than a seam, use a flathead screwdriver instead, pushing slowly so you do not strip the plastic.
Some fobs have a small button or release on the back. Press or slide it, and the battery compartment will pop out or the case will separate. If you cannot find a seam or slot after thirty seconds of looking, check your owner's manual or search for a video of your exact fob model opening—some designs are unusual enough that guessing can crack the case.
Once the fob is open, you will see the battery sitting in a small metal holder or clip. It is usually a thin silver coin about the size of a dime. Do not force anything; if the case does not come apart easily, you are probably prying in the wrong spot.
Remove the old battery and note its position
Before you touch the old battery, look at which side is facing outward. Most coin cells have a flat side and a domed side. The domed side usually faces up, but check yours. Take a mental note or take a photo with your phone so you remember the orientation when you install the new one.
Gently pry the old battery out with your fingernail or the edge of a coin. It should come out easily; if it is stuck, you may be pushing on the wrong side. Once it is out, set it aside. Do not throw it away yet—you may need to check the type if the printing is worn off.
Install the new battery in the correct direction
Place the new battery into the compartment with the same side facing outward as the old one. If the domed side faced up before, the domed side should face up now. Press down gently until you hear or feel a small click—that means the battery is seated in the metal clip and making contact.
Do not force the battery down. If it does not click after gentle pressure, flip it over and try the other way. One direction will feel right; the other will feel loose or wrong. Once it clicks into place, you are done with the battery itself.
Test the fob before closing it completely
Before you snap the case shut, press a button on the fob and watch for the light. Most fobs have a small LED that flashes when you press a button. If the light comes on, the battery is making good contact and the fob is working. If nothing happens, the battery may be in backwards or not seated properly—pop it out and try again.
Press each button on your fob—lock, unlock, trunk, panic—to make sure they all work. If one button does not light up, the battery is probably fine but that button may be worn out. Once all the buttons you use are working, you can close the fob.
Close the fob and check it in your car
Align the two halves of the fob and press them together firmly until they snap. You should hear a small click when they lock. Do not force them; if they do not come together smoothly, one half may be slightly misaligned—separate them and try again.
Walk to your car and test the fob from a few feet away. Press the lock button and listen for the doors to lock. Press unlock and listen for them to unlock. If the fob works from your normal distance, the battery is installed correctly and you are finished. If the fob only works from very close to the car, the battery may not be making full contact—open the fob again and reseat it.
Frequently Asked Questions
Can I use any coin cell battery, or does the exact type matter?
The exact type matters. CR2032, CR2025, and CR2016 are different thicknesses and will not work interchangeably. A battery that is too thick may not close the fob; one that is too thin may not make contact. Check your fob or manual for the correct type before you buy.
What do I do with the old battery?
Most coin cell batteries can go in your household trash, but some areas have battery recycling programs. Call your local waste management or check their website to see if they accept coin cells. If recycling is available, drop the old battery at a collection site rather than throwing it away.
How long does a key fob battery usually last?
A coin cell battery in a key fob typically lasts three to four years with normal use. If you use your fob many times a day, it may last only two years. If you use it rarely, it may last five years or longer. The battery will gradually weaken before it dies completely, so you may notice the fob only working from closer distances before it stops working entirely.
My fob still does not work after I changed the battery. What should I do?
First, open the fob again and make sure the battery is seated firmly in the clip and facing the right direction. If it is, try a different new battery—the one you bought may be defective. If a second battery does not work, the fob itself may be damaged or the circuit may be worn out, and you may need a replacement fob from your car dealer.
Can I damage my car by changing the battery myself?
No. The battery is isolated inside the fob and has no connection to your car's electrical system. Changing it cannot harm your car or its electronics. The only risk is breaking the fob case if you pry too hard, so work slowly and gently.