Replace the battery yourself in under five minutes

The battery in your Honda Odyssey key fob dies like any other battery—usually after three to four years of regular use. You can replace it yourself with nothing but a coin and a fresh battery from any drugstore or supermarket. The whole job takes about two minutes once you have the new battery in hand.

Your Odyssey key fob uses a CR2032 coin cell battery, the same flat, round battery found in calculators, watches, and greeting cards. You can buy a pack of them for a few dollars at any pharmacy, grocery store, or hardware store. Some auto parts stores carry them too, but the pharmacy is usually faster and cheaper.

Key Takeaways

  • Honda Odyssey key fobs use a CR2032 battery, which you can buy at any pharmacy or grocery store for a few dollars.
  • Open the fob by inserting a coin into the slot on the edge and twisting gently—do not pry with a screwdriver, which can crack the plastic.
  • Note which side of the old battery faces outward before you remove it, then install the new one the same way.
  • The fob should work when ready after you snap the two halves back together; if it does not, the battery may be installed upside down.

Locate the slot on the edge of your key fob

Look at the thin edge of your key fob where the two plastic halves meet. You will see a small slot cut into the plastic—this is where you insert a coin to open the fob. The slot runs horizontally along the edge, usually near the bottom half of the fob.

If you have an older Odyssey key fob, the slot may be less obvious. Run your finger around the entire edge until you feel a slight indentation or groove. Some fobs have a tiny arrow or line printed next to the slot to show you where to insert the coin.

Open the fob with a coin

Insert a flathead coin—a penny, dime, or quarter works equally well—into the slot. Push it in gently until you feel it catch, then twist the coin slowly, as if you were opening a jar lid. You are not forcing anything; the fob should open with light pressure. If you feel strong resistance, stop and check that the coin is fully seated in the slot.

As you twist, the two halves of the fob will separate slightly. Once you see a gap, you can remove the coin and use your fingernail or thumb to pry the halves apart the rest of the way. Do not use a screwdriver or other sharp tool—the plastic cracks easily, and you may damage the circuit board inside.

Remove the old battery and note its position

Inside the fob, you will see a small, flat, silver-colored battery sitting in a shallow cup or holder. Before you touch it, look at which side faces upward. The battery has a plus sign (+) printed on one side and a minus sign (−) on the other. Remember which side was facing up—this matters when you install the new battery.

Gently pry the old battery out of its holder using your fingernail or the edge of a coin. The battery is not glued down; it should lift out with light pressure. Set it aside. If the battery is stuck, try tilting the fob slightly so gravity helps it slide out.

Install the new CR2032 battery

Take your new CR2032 battery and orient it the same way the old one was facing. If the plus sign was facing up in the old battery, the plus sign should face up on the new one. Slide the new battery into the holder and press it down gently until it sits flat and level in the cup.

The battery should fit snugly but not require force. If you have to push hard, check that you are inserting it straight down and not at an angle. Once it is seated, the battery will not move around inside the fob.

Close the fob and test the buttons

Align the two halves of the fob so the edges line up evenly. Press them together firmly until you hear or feel a click—the fob will snap shut when the two halves are fully seated. You may need to explore steady pressure with both hands for a moment.

Press the lock and unlock buttons on your fob. You should hear the car respond when ready—the doors will lock or unlock, and you may hear a beep. If nothing happens, open the fob again and check that the battery is installed with the correct side facing up. Flip it over, close the fob, and test again.

What to do if the fob still does not work

If the fob does not respond after you have installed the new battery correctly, the problem is usually not the battery. The circuit board inside may have failed, or the buttons may be worn out. In this case, you will need a replacement fob from a Honda dealer or a third-party supplier.

Before you buy a new fob, try one more thing: clean the battery contacts inside the fob with a dry cloth or cotton swab. Sometimes a thin layer of corrosion or dust prevents good contact between the battery and the metal springs. Wipe both the battery and the metal contacts, then reinstall the battery and test again.

Frequently Asked Questions

Where can I buy a CR2032 battery?

Any pharmacy, grocery store, or drugstore carries CR2032 batteries in the watch and battery section. They cost between one and three dollars for a single battery, or you can buy a pack of several for five to ten dollars. Auto parts stores and hardware stores also stock them, usually near the checkout counter.

Can I use a different battery size?

No. Your Honda Odyssey key fob is designed specifically for a CR2032 battery. Using a different size will not fit in the holder, and using a battery with a different voltage can damage the circuit board. Always use CR2032.

How often do I need to replace the battery?

Most CR2032 batteries last three to four years in a key fob, depending on how often you use the buttons. If you use your fob several times a day, the battery may last only two to three years. If you use it rarely, it may last longer.

What if I crack the plastic when opening the fob?

Small cracks in the plastic housing do not usually affect how the fob works, but they can let moisture inside and damage the circuit board over time. If the crack is large or the fob no longer closes tightly, you may need to replace the entire fob. Minor cracks can be sealed with a small amount of clear epoxy or plastic cement.

Do I need to reprogram the fob after changing the battery?

No. Changing the battery does not erase the programming in your key fob. Once you install the new battery and close the fob, it should work when ready without any additional steps.