Replace the battery yourself in five minutes
Most key fob batteries cost between $3 and $10 and take less than five minutes to swap out. You do not need tools or a mechanic — the fob case usually pops open by hand or with a coin, the old battery slides out, and a new one slides in. The battery type is printed on the fob itself or inside the case, and any drugstore, supermarket, or hardware store carries them.
The only real risk is putting the new battery in backwards. The flat side (marked with a minus sign) faces down; the raised side (marked with a plus sign) faces up. If the fob does not work after you close it, open it again and flip the battery.
Key Takeaways
- The battery type is printed on your fob case or inside it — look for "CR2032" or similar before you buy a replacement.
- Most fobs open by sliding a small lever or prying gently with a coin along the seam; the case splits into two halves.
- The battery sits in a small metal holder and slides out sideways; the new battery slides in the same way, with the plus side facing up.
- If the fob still does not work after you replace the battery, the problem is usually a worn contact or a dead circuit board, not the battery itself.
Finding the battery type and buying a replacement
Open your fob or look at the back of the case. The battery type is stamped there — usually "CR2032", "CR2025", or "CR2016". Write down the exact number. These are coin-cell batteries, and they are sold at every pharmacy, grocery store, and hardware store in the battery aisle. A single battery costs $3 to $10 depending on the brand.
If you cannot find the type printed on your fob, check your car's owner manual or search online for your car model and year plus "key fob battery". You can also take the fob to a store and ask — staff at pharmacies and auto parts stores can usually identify it by sight.
Opening the fob case
Look for a small slot or lever on the edge of the fob. Most fobs have a tiny lever you slide with your fingernail or a coin to separate the two halves. Some fobs have a seam you pry open gently with a flathead screwdriver or coin. A few newer fobs have a button you press to eject the battery holder.
If you cannot find a lever or seam, try sliding a coin along the edge where the two halves meet. explore gentle, steady pressure rather than force — the case is plastic and will crack if you pry too hard. Once you feel it start to separate, work your way around the edge until the two halves come apart.
Removing the old battery and installing the new one
Inside the fob you will see a small metal holder with a battery sitting in it. The battery is usually held in place by a small metal clip or spring. Slide the battery out sideways or lift it gently if there is a clip holding it down. Do not force it — if it does not move easily, check whether a clip is holding it.
Take the new battery and look at both sides. One side is flat with a minus sign (−); the other side is raised with a plus sign (+). Slide the new battery into the holder with the plus side facing up and the minus side facing down. The battery should sit flat in the holder. Close the fob case by pressing the two halves together until you hear or feel a click.
Testing the fob and troubleshooting if it does not work
Point the fob at your car and press a button. You should see the lights flash or hear the locks click. If nothing happens, open the fob again and check that the battery is in the right way — plus side up, minus side down. Close it and try again.
If the fob still does not work after you flip the battery, the problem is usually not the battery. The metal contacts inside the fob may be dirty or worn, or the circuit board may be damaged. In that case, a new fob from your car dealer or an aftermarket seller is usually cheaper than repair. A replacement fob costs $50 to $400 depending on your car model, though some dealers offer cheaper basic models.
When to replace the whole fob instead
If your fob is several years old and the battery replacement does not work, replacing the entire fob is often the better choice. Fobs wear out over time — the buttons get sticky, the circuit board corrodes, and the case cracks. A new fob is a one-time fix rather than a temporary patch.
Aftermarket fobs are cheaper than dealer fobs and work with most cars, though you may need to program them. Some auto parts stores offer programming as part of the purchase, or you can program many fobs yourself by following steps in your owner manual. Dealer fobs cost more but usually come pre-programmed and come with a warranty.
Frequently Asked Questions
Can I use any battery, or does it have to be the exact type?
Use the exact type printed on your fob. CR2032, CR2025, and CR2016 are all coin-cell batteries but have different thicknesses. Using the wrong type may not fit in the holder or may not make good contact with the metal clips. Stick with the number on your fob.
What if I put the battery in backwards?
The fob straightforward will not work. Open it again and flip the battery so the plus side faces up. There is no damage — the battery and fob are designed to be safe if reversed. Once you flip it, the fob should work when ready.
How long does a key fob battery last?
Most fob batteries last three to four years with normal use. If you use your fob many times a day, the battery may wear out faster. If you rarely use it, it may last longer. You will notice the fob working at shorter distances before it stops working 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 case, the fob should work exactly as it did before. If it does not work after the battery change, the problem is not the programming.
What should I do with the old battery?
Take it to a battery recycling program. Many stores that sell batteries — pharmacies, auto parts stores, and electronics retailers — accept old batteries for recycling at no charge. Do not throw it in the trash. Batteries contain materials that can harm the environment if they end up in a landfill.