Most key fob batteries take five minutes to swap out yourself
You can replace a key fob battery without visiting a dealer or locksmith. The battery sits inside the plastic case, held in by a small clip or spring. You pry the case open, slide out the old battery, and slide in a new one—the whole job takes longer to find the right battery type than to do the work itself.
The battery type varies by car make and model. Common types are CR2032, CR2025, and CR2016 (the numbers refer to the battery's diameter and thickness). You can find the type printed on the battery itself once you open the fob, or check your owner's manual. A replacement battery costs $3 to $8 at any pharmacy, grocery store, or hardware store.
Key Takeaways
- Most key fob cases open by prying a small slot or seam with a coin or flathead screwdriver—check the edges and sides for a line that marks where the two halves meet.
- The battery sits in a metal holder with a clip or spring; note which side faces up before you remove it, because the new battery must go in the same way.
- Buy a replacement battery that matches the type number printed on the old one, usually CR2032 or CR2025.
- Test the fob before you close it fully—press each button to confirm the lock and unlock functions work at normal range.
Locate the seam and open the case
Look at the edges of your key fob for a thin line or slot that runs around the perimeter. This seam marks where the plastic case splits into two halves. On most fobs, the seam runs horizontally around the middle, but some models have it on the side or along the top edge. Run your fingernail or a coin along the edges until you feel where the two halves meet.
Insert a flathead screwdriver or coin into the seam and gently twist to pry the case apart. Do not force it—if you meet hard resistance, you may be at the wrong spot. Try another section of the seam. Once you find the right spot, the case usually pops open with light pressure. Set both halves on a clean surface where you can see the battery.
Remove the old battery and note its position
The battery sits in a metal holder, usually with a small spring or clip holding it in place. Before you touch it, look at which side faces up—the positive side (marked with a + symbol) or the negative side. This matters because the new battery must go in the same way, or the fob will not work.
Gently lift the spring or clip and slide the old battery out. If the clip is stiff, use a plastic spoon handle or your fingernail rather than a metal tool, which can scratch the holder. Once the old battery is out, look at the number printed on it. This is the battery type you need to buy.
Buy and install the replacement battery
Take the old battery to a pharmacy, grocery store, or hardware store and buy a new one with the same type number. CR2032 is the most common type across car brands, but always match the number on your old battery. A single replacement battery costs between $3 and $8. Some stores sell them in multipacks if you want spares.
Slide the new battery into the metal holder with the same side facing up as the old one. The battery should sit flat and flush with the holder. If it does not sit evenly, remove it and flip it over—you may have inserted it upside down. Once it is seated, the spring or clip should hold it in place without you having to push hard.
Test the fob before closing the case
Press the lock button and listen for the car to lock. Press the unlock button and listen for the car to unlock. If both buttons work and the car responds at your normal range (usually 20 to 30 feet), the battery is installed correctly. If nothing happens, remove the battery and check that it is facing the right direction.
If the fob still does not work after flipping the battery, the problem may not be the battery. The fob could have a worn button contact, water damage, or a broken circuit board. In that case, you will need a replacement fob from a dealer or locksmith. But if the buttons work, you are done—close the case and you are finished.
Close the case and check the seal
Line up the two halves of the case so the seam is even all the way around. Press them together firmly until you hear or feel a click. The case should be snug with no gaps. If there are gaps, the case is not fully closed—press harder or check that you have aligned the halves correctly.
Once the case is closed, press each button one more time to confirm everything still works. The fob is now ready to use. If you notice the battery draining faster than before, or if buttons stop responding within a few weeks, the battery may be defective—return it to the store and ask for a replacement.
Frequently Asked Questions
What if I cannot find the seam on my key fob?
Some fobs have a very thin seam that is hard to see. Try running your fingernail around every edge, including the top and bottom. If you still cannot find it, check your owner's manual—it may show a diagram of where the seam is. You can also search online for "[your car make and year] key fob battery replacement" to see photos of the exact model.
Can I use a different battery type if I cannot find the exact one?
No. Battery types like CR2032 and CR2025 look similar but have different thicknesses and voltages. Using the wrong type can damage the fob's circuit board or cause the buttons to work intermittently. Always match the type number on your old battery.
How often do I need to replace the battery?
Most key fob batteries last three to four years with normal use. If you use the fob heavily or leave it in a hot car, the battery may drain faster. You will know it is time to replace it when the fob stops working at your normal range or when buttons become unresponsive.
What should I do with the old battery?
Do not throw it in the trash. Most pharmacies and electronics stores have battery recycling bins near the checkout. You can also take it to a local hazardous waste collection site. Batteries contain materials that can harm the environment if they end up in a landfill.
Why is my new battery not working?
The most common reason is that the battery is installed upside down. Remove it and flip it so the opposite side faces up. If that does not work, try a different new battery from a different package—the first one may have been defective. If a second battery does not work, the fob itself may be damaged and need replacement.