Most key fob batteries cost $3 to $8 and take less than five minutes to swap
You can change your key fob battery yourself without tools, a trip to the dealership, or a mechanic visit. The battery itself costs a few dollars at any pharmacy, grocery store, or hardware store. The whole job takes the time it takes to open the fob, remove the old battery, and snap in the new one — usually under five minutes.
The catch is that every fob design is different. Some pop open with a coin. Others have a hidden seam you slide a fingernail into. A few require a small screwdriver. Once you know which type you have, the rest is straightforward.
Key Takeaways
- Most key fob batteries are CR2032, CR2025, or CR2016 — check your owner's manual or the old battery itself to know which one to buy.
- Fobs open three ways: a coin slot on the edge, a hidden seam along the side, or a small screw on the back — your manual shows which yours uses.
- When you open the fob, note which side of the battery faces up before you remove it, then install the new one the same way.
- If the fob still does not work after a new battery, the problem is usually a corroded contact or a broken button, not the battery itself.
Find out what battery your fob needs
The battery type is printed on the old battery itself. If you have not opened the fob yet, check your owner's manual — it lists the battery model in the key fob section. The three most common types are CR2032 (the largest), CR2025, and CR2016 (the smallest). They cost between $3 and $8 for a single battery or a pack of two.
Buy the battery before you open the fob. That way you have it ready and you are not hunting for a store while the fob is sitting open on your table. Most pharmacies, grocery stores, and hardware stores stock all three types in the watch battery or electronics aisle.
Identify how your fob opens
There are three common designs. The first has a coin slot on the edge — you insert a coin and twist it like a bottle cap to pop the two halves apart. The second has a seam running along the side or back — you slide a fingernail or a plastic spoon into the seam and gently pry until the halves separate. The third has a small screw (usually Phillips head) on the back that you remove with a screwdriver.
Your owner's manual shows which design yours is. If you do not have the manual, search online for "[your car make and year] key fob battery" — the first result usually shows the opening method with a photo. Do not force it. If you are prying and it is not budging, you probably have the coin-slot type instead.
Open the fob and note the battery position
Once you know the opening method, open it gently. The two halves are usually held together by a small clip or just friction — they separate easily once you find the right angle. Set both halves on a clean surface where you will not lose the small spring or clip that sometimes falls out.
Before you touch the battery, look at which side is facing up. The battery has a flat side (negative) and a rounded side (positive). Take a photo with your phone if you are unsure — you will install the new battery the same way. This matters. A battery installed backwards will not work.
Remove the old battery and install the new one
Gently pry the old battery out with your fingernail or a plastic spoon. Do not use a metal tool — you can damage the contact underneath. Once it is out, check the metal contact where the battery sat. If it looks green or corroded, wipe it clean with a dry cloth or a pencil eraser.
Slide the new battery in with the same side facing up as the old one was. It should sit flat and snug. You do not need to force it. Close the fob halves back together — they usually click or snap into place. Test the buttons. If the fob works, you are done. If it does not, see the troubleshooting section below.
What to do if the fob still does not work
A new battery fixes most dead fobs. If yours still does not respond, the problem is usually not the battery. The most common culprit is a corroded contact inside the fob — the metal piece the battery touches. If you saw green or white corrosion when you opened it, clean it with a pencil eraser or a cotton swab dipped in rubbing alcohol. Let it dry completely, then reinstall the battery.
The second most common issue is a broken button contact. If one button works but others do not, the rubber button pad inside may be worn out. This requires a replacement pad or a new fob — neither is a battery job. If no buttons work at all, the fob's circuit board may be damaged, which also means replacing the fob itself.
If you have tried a new battery and cleaned the contacts and the fob still does not work, the fob itself has failed. A replacement fob from a dealership costs $200 to $500. Aftermarket fobs cost $30 to $100 and work with most cars, though some require programming at a dealership.
Frequently Asked Questions
Can I use a different battery type if I cannot find the right one?
No. CR2032, CR2025, and CR2016 are different thicknesses and will not fit properly or work correctly if you use the wrong one. They cost the same and are all widely available — buy the correct type for your fob.
What if I lost the small spring or clip when I opened the fob?
If it is a spring under the battery, you need it — the fob will not work without it. Check the floor and your work surface carefully. If you cannot find it, you will need a replacement fob or a trip to a dealership to get the spring replaced. If it is a clip holding the halves together, the fob will still work but may feel loose.
How often do I need to change the battery?
Most key fob batteries last three to four years with normal use. If you use the fob heavily — pressing buttons many times a day — it may need a new battery every two years. You will notice the buttons becoming less responsive before the battery dies completely.
Is it safe to change the battery myself?
Yes. There is no risk to you or the car. The battery is small and low-voltage. The only risk is damaging the fob itself if you force it open or use a metal tool on the contacts. Work slowly and gently, and you will be fine.