You can replace a Prius key fob battery yourself in about two minutes
The battery in your Prius key fob will eventually run down, and when it does, you do not need a dealer visit or special tools. The fob opens with a coin or flat screwdriver, the battery slides out, and a new one slides in. The whole job takes longer to find the right battery than to install it.
Most Prius key fobs use a CR2032 battery, a flat coin-cell battery about the size of a dime. You can buy these at any drugstore, supermarket, or hardware store for between $3 and $8 for a pack of two or four. Some older Prius models use a CR2016 instead, so check your fob or owner's manual first if you want to be certain.
Key Takeaways
- Prius key fobs almost always use a CR2032 coin-cell battery, available at any drugstore or supermarket for a few dollars.
- Open the fob by inserting a coin or flat screwdriver into the slot on the edge and twisting gently until the two halves separate.
- Note which side of the battery faces up before you remove it, then slide the new battery in the same way.
- The fob does not need to be reprogrammed after a battery change — it will work when ready once you close it back up.
How to open the key fob
Look at the edge of your Prius key fob for a small slot or seam running around the perimeter. This is where the two halves of the fob meet. Insert a coin (a dime or penny works well) or a flat-head screwdriver into that slot, positioning it so the edge of the coin or blade sits in the seam.
Twist the coin or screwdriver gently — you are not forcing it, just explore steady pressure. The two halves will separate. If it does not budge after a few seconds of gentle twisting, try a different spot along the seam; sometimes one side gives more easily than the other. Once the halves are apart, set the smaller piece aside in a safe place where you will not lose the spring or internal parts.
Removing and replacing the battery
Inside the fob, you will see the battery sitting flat against the plastic. Before you touch it, note which side is facing up — the positive side (marked with a + symbol) or the negative side. This matters because the battery must go back in the same way.
Slide the old battery out with your fingernail or the edge of a coin. If it is stuck, a tiny bit of gentle prying with a plastic tool (not metal, which can damage the fob) will free it. Slide the new CR2032 battery in with the same side facing up as the old one was. The battery should sit flat and flush with the plastic housing.
Closing the fob and testing it
Line up the two halves of the fob so the seam is even all the way around. Press them together firmly until you hear or feel a click. The fob should be snug and not rattle. Press the lock and unlock buttons a few times to confirm the fob is working — you should see the lights on your Prius respond.
If the buttons do not work, open the fob again and check that the battery is sitting flat and facing the correct direction. Batteries installed backwards will not make contact with the terminals inside. Once the fob works, you are done; no reprogramming is needed.
What to do if your fob still does not work
If a fresh battery does not bring the fob back to life, the problem is usually not the battery itself. The most common cause is corrosion or dirt on the battery contacts inside the fob. Open the fob again and look at the small metal contacts where the battery sits. If they look dark, discolored, or crusty, wipe them gently with a dry cotton swab or the corner of a clean cloth.
If the contacts are clean and a new battery still does not work, the fob's internal circuit may be damaged. This is rare, but it happens if the fob has been dropped, sat in water, or straightforward worn out after years of use. In that case, you will need a replacement fob from a Prius dealer or a third-party supplier. A new aftermarket fob typically costs $40 to $100 and may need to be programmed to your vehicle.
Buying the right battery
CR2032 batteries are standard and sold everywhere — drugstores, supermarkets, hardware stores, and online retailers all stock them. You do not need a special "car battery" or "key fob battery"; a regular CR2032 coin cell works fine. Brands like Duracell, Energizer, and store brands all perform the same way for this use.
If you are unsure whether your fob uses a CR2032 or a different size, check your Prius owner's manual or look up your model year and generation online. You can also open the fob and measure the old battery before you buy a new one, or take the old battery to the store and match it to the new one on the shelf.
Frequently Asked Questions
How often do I need to replace the battery in my Prius key fob?
Most key fob batteries last between three and four years with normal use. If you use the fob heavily — pressing the buttons many times a day — the battery may wear out sooner. You will notice the buttons becoming less responsive or the range of the fob shrinking before the battery dies completely.
Can I use a different size battery if I cannot find a CR2032?
No. Using the wrong size battery can damage the fob or cause it to malfunction. CR2032 batteries are inexpensive and widely available, so it is worth waiting a day or two to get the correct one rather than forcing a different size into the fob.
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 close the fob back up and the battery makes contact, it will work when ready without any additional steps.
What should I do with the old battery?
Most retailers that sell batteries — drugstores, supermarkets, and electronics stores — have battery recycling bins near the checkout or customer service desk. You can also check Earth911.com or your local waste management website for recycling locations near you.
Why is my key fob not working even though I just put in a new battery?
The most common reason is that the battery is installed backwards. Open the fob and check that the positive side (marked with a +) is facing the same direction as the old battery was. If the battery is correct and the fob still does not work, the metal contacts inside may be dirty — wipe them with a dry cloth and try again.