Most car key fob batteries take five minutes to replace yourself
You can change a car key fob battery without tools, without a trip to the dealer, and without spending more than a few dollars. The battery sits behind a removable cover on the fob itself. You pry the cover open with a coin or your fingernail, slide out the old battery, and slide in a new one — the whole job takes longer to find where you put the new battery than to do the swap.
The battery type varies by car make and model. Most fobs use a coin-cell battery, which looks like a small silver disc. The most common sizes are CR2032, CR2025, and CR2016. You can buy a replacement at any pharmacy, grocery store, or hardware store for between $3 and $8. Some fobs use two batteries instead of one, and a few older models use AA or AAA batteries, but the process is the same.
Key Takeaways
- Most key fob batteries are coin-cell types (CR2032 is the most common) and cost $3 to $8 at any pharmacy or grocery store.
- You open the fob by prying the seam with a coin, flathead screwdriver, or your fingernail — no special tools needed.
- Note which side of the battery faces up before you remove it, because the new battery must go in the same way.
- If the fob still does not work after you replace the battery, the problem is likely a worn contact or a broken circuit board, not the battery itself.
Finding out what battery your fob needs
The easiest way is to look at the fob itself. Most manufacturers print the battery type on the inside of the cover or on the battery compartment itself. Open the fob (see the next section) and look for a code like CR2032 or CR2025 stamped or printed near where the battery sits.
If there is no marking, check your car's owner manual. The manual lists the battery type in the key fob section, usually near the back. If you do not have the manual, search online for "[your car year, make, and model] key fob battery type" — you will find the answer in seconds.
You can also take the old battery to any pharmacy or store that sells batteries and ask them to match it. They will identify the type and sell you a replacement on the spot.
How to open the fob and remove the old battery
Look for a seam running around the edge of the fob. This is where the two halves of the plastic case meet. Slide a coin (a dime or penny works) into the seam and twist gently to pry the two halves apart. You can also use a flathead screwdriver or even your fingernail if you have a good grip. Do not force it — if you feel strong resistance, you may be prying in the wrong spot.
Once the fob opens, you will see the battery sitting in a small metal or plastic holder. Before you touch it, look at which side is facing up. The side with the + symbol should face either up or down depending on your fob design — you need to remember this because the new battery must go in the same way.
Slide the old battery out of its holder. If it is stuck, use your fingernail or a plastic tool to gently pry one edge up. Do not use a metal tool that could scratch the circuit board inside.
Installing the new battery
Slide the new battery into the holder with the + side facing the same direction as the old battery did. Push it in until it sits flat and snug in the holder. You should hear or feel a small click when it seats properly.
Close the fob by pressing the two halves together until they snap. You may hear a click or feel them lock into place. Test the fob by pressing each button — the lock, unlock, and panic buttons should all work right away.
What to do if the fob still does not work
If the buttons do not respond after you install the new battery, the problem is not the battery. The most common cause is a worn contact — the small metal piece inside the fob that touches the battery. Over time, dirt or corrosion builds up on this contact and blocks the electrical connection.
You can try cleaning the contact with a pencil eraser or a cotton swab dipped in rubbing alcohol. Rub the metal contact gently until it looks shiny, then let it dry completely before you close the fob and test it again.
If cleaning does not work, the circuit board inside the fob may be damaged, or the buttons themselves may be worn out. At that point, you need a replacement fob. You can buy an aftermarket fob online for $15 to $40, or order one from your car dealer for $50 to $150 depending on the model. Some aftermarket fobs work with multiple car brands, so check the listing to make sure it matches your car.
How long a key fob battery lasts
A typical coin-cell battery in a key fob lasts three to four years. Heavy users — people who press the buttons many times a day — may need to replace the battery sooner. Light users may get four or five years out of one battery.
You will notice the fob starting to fail before the battery dies completely. The buttons may require harder presses, or they may work only from very close to the car. When you see this, the battery is running low and a replacement is coming soon.
Frequently Asked Questions
Can I use any CR2032 battery, or does it have to be a specific brand?
Any CR2032 battery works in any fob that takes a CR2032. Brand does not matter — Duracell, Energizer, Amazon Basics, and store brands all perform the same. Buy whatever is cheapest or most available where you shop.
What if I put the battery in backwards?
The fob straightforward will not work. The battery will not make electrical contact if the + side faces the wrong direction. If you close the fob and nothing happens, open it again and flip the battery around. It should work when ready.
Is it safe to replace the battery myself, or should I go to the dealer?
It is completely safe. There is no risk of electric shock, and you cannot damage the fob by opening it. The dealer will charge you $50 to $100 for the same five-minute job. Doing it yourself saves money and time.
Do I need to reprogram the fob after I change the battery?
No. Changing the battery does not erase the fob's programming. It will work exactly as it did before, as soon as you install the new battery and close the case.