You can replace a Honda key fob battery yourself in about five minutes
Most Honda key fobs use a coin-cell battery—usually a CR2032 or CR2025—that you can buy at any drugstore, grocery store, or hardware store for a few dollars. The fob itself has a small slot or seam where the two halves separate, and once you open it, the old battery slides out and a new one slides in. You do not need any tools beyond your fingernail or a plastic spoon handle, and you do not need to visit a dealer.
The exact steps depend slightly on which Honda model you own and which generation of key fob came with it, but the process is nearly identical across all of them. This guide covers the most common design—a fob with a seam running around the edge—and points out what to do if yours looks different.
Key Takeaways
- Honda key fobs almost always use a CR2032 or CR2025 coin-cell battery, which costs two to five dollars and is sold at any pharmacy or supermarket.
- The fob opens by sliding a plastic spoon handle or your fingernail into the seam around the edge and gently twisting to separate the two halves.
- Once open, the battery sits in a small metal holder and lifts straight out; the new battery goes in the same way, with the flat side facing up.
- After closing the fob, test all buttons before you put the old battery in the trash, because a dead battery can sometimes be revived by cleaning the contacts.
What battery your Honda key fob uses
The vast majority of Honda key fobs made in the last 20 years use either a CR2032 or CR2025 coin-cell battery. Both are 20 millimeters across and look identical at a glance; the difference is thickness (3.2 millimeters versus 2.5 millimeters). If you are not sure which one your fob needs, open the fob first and look at the battery itself—the size is printed on the metal case.
If you cannot open the fob or the battery does not match either of those two types, your Honda is older or uses an unusual design. In that case, bring the fob to any Honda dealer or call their parts department with your vehicle's year and model; they can tell you the correct battery in one call and usually have it in stock.
How to open the key fob
Look at the edge of your key fob for a thin seam running around the perimeter. This is where the two plastic halves meet. Slide the flat edge of a plastic spoon handle, a butter knife, or your fingernail into that seam on one side of the fob. Do not use a metal screwdriver or a sharp blade—you risk cracking the plastic or scratching the circuit board inside.
Once the edge is in the seam, gently twist the spoon handle or your hand to create a small gap. You are not trying to pry it open violently; just enough pressure to separate the halves by a quarter inch. Once there is a gap, move to another spot on the seam and repeat until the fob comes apart. The two halves should separate cleanly without cracking.
If the fob does not budge after gentle pressure on all sides, stop and check whether there is a small screw hidden under a rubber pad or sticker on the back. Some older Honda fobs have a single screw instead of a snap-together design. If you find one, use a small Phillips screwdriver to remove it, then the halves will come apart.
Removing the old battery and installing the new one
Once the fob is open, you will see the battery sitting in a small metal holder, usually in the center of the circuit board. The battery is a flat silver coin about the size of a dime. Gently lift one edge of the battery with your fingernail or the spoon handle to pop it out of the holder. It should come free with very light pressure—if it is stuck, do not force it. Instead, check whether there is a small plastic tab holding it down; if so, slide the tab to the side first.
Before you throw away the old battery, set it aside for a moment. Take your new CR2032 or CR2025 battery and look at both sides: one side is flat and unmarked, and the other side has a plus sign (+) printed on it. The flat side should face up (toward the top of the fob when you are holding it in front of you). Slide the new battery into the metal holder with the flat side up, and it will click into place.
If the new battery does not sit flat or feels loose, you may have installed it upside down. Pop it out and flip it over. The battery should sit snugly in the holder without any rocking or movement.
Closing the fob and testing the buttons
Line up the two halves of the fob so the seams match on all sides. Press them together firmly until you hear or feel a click. You may need to explore pressure on multiple spots around the edge to make sure all the snap points engage. Once it is closed, the fob should feel solid and not flex or rattle when you squeeze it gently.
Before you put the old battery in the trash, test every button on the fob—lock, unlock, panic, trunk, or whatever buttons your model has. Point the fob at your car from about 20 feet away and press each button. You should see the car's lights flash or hear the locks click. If nothing happens, the new battery may be installed upside down, or the battery itself may be defective. Open the fob again, check that the flat side of the battery is facing up, and test again. If it still does not work, try a different new battery from a different package.
What to do if the fob still does not work
If you installed the battery correctly and tested it with a fresh battery from a new package, the problem is likely inside the fob itself. The most common issue is dirty contacts—the small metal strips inside the fob that touch the battery. Over time, dust or corrosion can build up and prevent the battery from making a good connection.
To clean the contacts, open the fob again and look for two or three small metal strips or pads inside the battery holder. Use a clean, dry cotton swab or a pencil eraser to gently rub each contact. Wipe away any dust or dark discoloration, then close the fob and test again. If the buttons still do not work after cleaning, the circuit board itself may be damaged, and you will need a replacement fob from a Honda dealer.
When to replace the whole fob instead
If your fob is very old, cracked, or has water damage, replacing just the battery may not be worth the effort. Water inside the fob will corrode the circuit board and contacts, and a new battery will not fix that. Similarly, if the buttons are stuck or do not click when you press them, the mechanical switches inside are worn out and a new battery will not help.
In those cases, a replacement fob from a Honda dealer is the better choice. Prices vary by model year, but most Honda key fobs cost between 100 and 300 dollars. Some dealers can program a new fob to your car on the spot; others may need to order one. Call your local Honda service department with your vehicle's year, make, and model to get a price and timeline.
Frequently Asked Questions
Can I use a different battery size if I cannot find a CR2032?
No. A CR2025 is thinner and may work in some fobs, but a CR2016 or any other size will not fit properly or may not provide enough power. Stick with CR2032 or CR2025, and check the old battery to see which one your fob uses. Both are common and sold everywhere.
How long does a Honda key fob battery last?
Most coin-cell batteries last three to four years with normal use. If you use your fob many times a day, the battery may wear out in two years. If you rarely use it, it may last five years or longer. There is no way to predict exactly when it will die, so keep a spare battery at home once you know which type your fob needs.
What if I drop the battery or lose it while changing it?
Coin-cell batteries are small and straightforward to lose on a carpet or under furniture. If you drop the old battery, use a flashlight and look carefully on the floor and under nearby furniture. If you cannot find it, just buy a new CR2032 or CR2025 and install that instead. The old battery is not worth searching for more than a minute or two.
Do I need to reprogram my key 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 fob, it should work when ready without any reprogramming. If it does not work, the problem is the battery installation or a dead battery, not the programming.
Is it safe to touch a coin-cell battery with my bare hands?
Yes. Coin-cell batteries are safe to handle with bare hands. They produce very little current and will not shock you. Wash your hands after handling the battery if you prefer, but there is no health risk from touching it briefly.