Most key fob batteries take five minutes to swap out yourself

A dead key fob battery is one of the easiest car problems to fix at home. You do not need tools or special knowledge — just the right battery type and a way to open the fob case. The whole job takes about five minutes, and a replacement battery costs between $3 and $10.

The hardest part is usually figuring out which battery your fob needs. Car key fobs almost always use coin-cell batteries, which are small, flat, and round. The most common types are CR2032, CR2025, and CR2016 — the numbers tell you the size and voltage. Once you have the right battery, opening the fob and swapping it out is straightforward.

Key Takeaways

  • Check your owner's manual or the fob case itself to find the exact battery type your car needs — usually CR2032, CR2025, or CR2016.
  • You can buy the correct battery at any pharmacy, grocery store, or hardware store for $3 to $10, or order it online.
  • Most fobs open by sliding a small lever, prying at a seam with a coin, or unclipping a plastic case — no screwdriver needed.
  • Note which side of the battery faces up before you remove it, then install the new one the same way and close the case.
  • If the fob still does not work after a new battery, the problem is likely a broken button contact or water damage, not the battery itself.

Find out what battery type your fob uses

The easiest way is to look at the fob itself. Open it (see the next section for how) and look at the battery that is currently inside. The battery type is printed on the flat side — you will see something like "CR2032" or "CR2025". Write that number down or take a photo with your phone.

If the battery is dead and you cannot read it, check your owner's manual. Search the index for "key fob" or "remote battery" and it will tell you the type. You can also call your car's dealership with your vehicle identification number (VIN) and they will tell you over the phone, though this takes longer than checking the manual.

Once you know the type, buy a replacement at a pharmacy, grocery store, hardware store, or online. Coin-cell batteries are sold everywhere — you do not need to go to a dealership or car parts store. Make sure the package says the exact type you need.

Open the key fob case

Key fobs open in three main ways, depending on the design. The most common is a small slot or lever on the edge of the fob. Look around the seam where the two halves meet — you may see a tiny slot that fits a coin or a lever you can slide with your fingernail. Slide or press it and the case will pop open.

If there is no slot or lever, try prying gently at the seam with a coin, a plastic spoon, or a plastic pry tool. Work your way around the edge slowly — do not force it or you may crack the plastic. The two halves should separate after a little pressure.

Some fobs have a screw or two holding the case together. If you see screw heads, use a small Phillips or flathead screwdriver to remove them. Keep the screws in a small dish so you do not lose them — you will need them to close the fob again.

Remove the old battery and install the new one

Once the case is open, you will see the battery sitting in a small metal holder or slot. Before you touch it, note which side is facing up — the side with the + symbol or the flat printed side. This matters because the battery only works one way.

Gently pry the old battery out with your fingernail or a plastic tool. Do not use a metal screwdriver because you might damage the metal contacts inside the fob. Once it is out, set it aside.

Take the new battery and place it in the same position as the old one, with the same side facing up. It should sit flat in the holder. Press down gently until you hear or feel a small click — that means it is seated properly.

Close the fob and test it

If your fob has a sliding lever or slot, push it back into place until it clicks. If it has a removable case, line up the two halves and press them together firmly until they snap shut. If there were screws, replace them now and tighten them snugly — do not over-tighten or you may strip the plastic.

Stand a few feet away from your car and press a button on the fob. You should see the lights flash or hear the locks click. If the fob works, you are done. If it does not, try pressing the button a few more times — sometimes a new battery needs a moment to make full contact.

What to do if the fob still does not work

If a new battery does not fix the problem, the issue is not the battery itself. The most common cause is a worn or corroded button contact inside the fob. Over time, the rubber button pads wear down and stop making good electrical contact. This is not something you can fix at home — the fob needs to be repaired or replaced.

Another possibility is water damage. If the fob has been dropped in water or exposed to moisture, the circuit board inside may be corroded. Again, this requires professional repair or replacement.

If your fob is old or the repair cost is high, it may be cheaper to buy a replacement fob from a dealership or an aftermarket supplier. Aftermarket fobs are usually less expensive than dealership ones and work just as well. Your car's dealership can program a new fob to your vehicle, or some locksmiths can do it as well.

Frequently Asked Questions

Can I use a different battery type if I cannot find the exact one?

No — use only the battery type specified for your fob. Different coin-cell batteries have different voltages and sizes, and using the wrong one may damage the fob's circuit board or cause the buttons to malfunction. If you cannot find the exact type locally, order it online — it will arrive in a day or two.

How long does a key fob battery last?

Most key fob batteries last three to four years with normal use. If you use the fob heavily — pressing buttons many times a day — the battery may wear out sooner. There is no way to extend the battery life, so plan to replace it every few years.

Is it safe to handle a coin-cell battery with my bare hands?

Yes, coin-cell batteries are safe to touch. They are not toxic and do not carry enough current to shock you. Just avoid touching both the + and − sides at the same time with metal objects, as this can cause a short circuit and drain the battery quickly.

What should I do with the old battery?

Take the old battery to a pharmacy, grocery store, or hardware store — most have a battery recycling bin near the checkout or customer service desk. Do not throw it in the trash. Batteries contain materials that should not go to a landfill.

Can a dealership replace the battery for me?

Yes, but it will cost more than doing it yourself — usually $20 to $50 in labor plus the battery cost. Since the job takes only a few minutes and requires no special tools, most people save money by replacing it at home.