Most key fob batteries take five minutes to replace at home
You can change a key fob battery yourself without tools or a trip to the dealership. The battery compartment is usually on the back or side of the fob, held closed by a small slot or screw. Once you open it, you slide out the old battery, note which side faces up, and slide in a new one of the same type. The whole job takes about five minutes and costs between two and ten dollars.
The hardest part is finding the right battery type for your fob. Car manufacturers use different sizes—the most common are CR2032, CR2025, and CR2016. You can find the type printed on the old battery itself, or check your car's manual. Any pharmacy, grocery store, or hardware store sells these batteries in the battery aisle.
Key Takeaways
- Open the key fob by locating the slot or seam on the back or side and gently prying it apart with a coin or plastic tool.
- Write down or photograph which direction the battery sits before you remove it, because the new one must face the same way.
- The battery type is printed on the old battery itself—common types are CR2032, CR2025, and CR2016.
- After inserting the new battery, test the fob before closing it completely to make sure all buttons work.
How to open the key fob without damaging it
Most key fobs split into two halves along a seam or slot. Look for a thin line running around the edge of the fob—this is usually on the back or the side. You do not need to force it. A coin, a plastic spoon handle, or a plastic pry tool works best; avoid metal screwdrivers, which can scratch the plastic or slip and damage the circuit board inside.
Insert your tool gently into the slot and twist slightly, the way you would open a paint can. The two halves should separate with light pressure. If it does not budge after a gentle try, rotate the fob and look for a different seam—some fobs have the split on the side rather than the back. Once the halves are apart, set the front half (the one with the buttons) face-down on a clean surface so nothing falls out.
Removing and replacing the battery
The battery sits in a small metal or plastic holder inside the fob. Before you touch it, take a photo or make a quick note of which side faces up—the flat side or the side with the raised bump. This matters. Slide the battery out gently with your fingernail or a plastic tool. If it is stuck, a tiny dab of rubbing alcohol on the edge can help it slide free.
Check the battery type printed on the old battery and compare it to the new one to make sure they match. Slide the new battery into the holder with the same side facing up as the old one was. The battery should sit flat and snug. If it falls out when you tilt the fob, you have it upside down—flip it and try again.
Testing before you close the fob
Before you snap the two halves back together, hold the fob in front of you and press each button—lock, unlock, panic, trunk, or whatever your fob has. You should see a small red light blink inside the fob when you press a button. If you see nothing, the battery is probably upside down. Flip it and test again.
If the light still does not appear, the new battery may be dead (rare, but it happens), or the fob may have a different problem. Try a different new battery from a different package before you assume the fob is broken. Once all buttons produce a light, you can close the fob.
Closing the fob and reassembling
Align the two halves so the seams match up evenly all the way around. Press down firmly and evenly—you should hear or feel a small click as the halves snap together. Do not force it; if it does not close smoothly, the battery may be sitting at an angle. Open it again, reseat the battery, and try closing once more.
Once closed, test the fob one more time from a distance. Stand near your car and press the lock button—your car should respond. If it does not, open the fob again and check that the battery is still seated correctly. Sometimes the battery shifts slightly during reassembly.
Common mistakes that prevent the battery from working
The most common error is installing the battery upside down. The flat side and the bump side look similar, and it is straightforward to reverse them. That is why photographing the old battery before removal saves time. The second mistake is not closing the fob all the way, which breaks the electrical contact inside. If your fob works for a few days and then stops, open it and make sure both halves are fully seated.
A third mistake is buying the wrong battery type. CR2032, CR2025, and CR2016 look almost identical but are different thicknesses. If you buy a CR2025 when your fob needs a CR2032, it will not make good contact. Always check the number printed on the old battery. If the old battery is too worn to read, check your car's manual or call the dealership with your car's year, make, and model.
Where to buy replacement batteries
Key fob batteries are sold in the battery aisle at pharmacies, grocery stores, hardware stores, and big-box retailers. Prices range from two to ten dollars depending on the brand and where you shop. Pharmacy chains like CVS and Walgreens usually stock CR2032, CR2025, and CR2016. Walmart, Target, and Home Depot carry them as well. You can also order them online, but if your fob is dead now, a store trip is faster.
Buy a name-brand battery if you can—Energizer, Duracell, and Panasonic are reliable. Generic batteries work too, but they sometimes have shorter lifespans. A good battery should last three to four years before the fob stops responding to button presses.
When to take your fob to a dealership instead
If you open the fob and the battery compartment looks corroded or wet, or if the circuit board is visibly damaged, a new battery will not fix it. Corrosion usually appears as a white, green, or blue crusty coating on the metal contacts. If you see this, the fob may need professional repair or replacement. Your car dealership can order a new fob, though it usually costs between 200 and 500 dollars depending on your car's make and model.
If you replace the battery, close the fob, and the buttons still do not work, and you have tried a second new battery from a different package, the fob itself may be broken. A dealership can test it and tell you whether repair or replacement makes sense. Some newer cars also allow you to reprogram a spare fob yourself using a sequence of button presses—your car's manual will explain this if your car supports it.
Frequently Asked Questions
How do I know which battery type my key fob uses?
The battery type is printed directly on the old battery—look for a code like CR2032, CR2025, or CR2016. If the old battery is too worn to read, check your car's owner manual or call your dealership with your car's year, make, and model. They can tell you the correct type in one call.
Can I use a different battery type if I cannot find the exact one?
No. CR2032, CR2025, and CR2016 are different thicknesses and will not make proper contact in the wrong fob. Using the wrong type may damage the fob or cause the buttons to work intermittently. Always match the type printed on your old battery.
What if the battery light does not blink after I install a new one?
The battery is probably upside down. Remove it, flip it so the opposite side faces up, and reinstall it. Test again. If the light still does not appear, try a new battery from a different package—the first one may be defective. If a second battery also does not work, the fob may have internal damage and need professional repair.
How long does a key fob battery last?
A good battery usually lasts three to four years, depending on how often you use the fob. Fobs used several times a day may need a new battery sooner. You will notice the range getting shorter—you have to stand closer to your car for the buttons to work—before the fob stops working entirely.
Can I replace the battery in a smart key or push-button fob?
Yes, the process is the same. Smart keys and push-button fobs also use coin-cell batteries like CR2032. Open the fob the same way, note the battery direction, and replace it. If your smart key has a physical key blade inside, be careful not to lose it when you open the fob.