The battery in your Prius key fob is replaceable without going to a dealer
Your Prius key fob runs on a small coin-cell battery, usually a CR2032 or CR2016, that you can buy at any drugstore or supermarket for a few dollars. You do not need special tools or a dealer appointment — the fob is designed to open from the side, and the battery slides out and in. The whole job takes about two minutes once you have the new battery in hand.
The exact battery type depends on your model year and which fob you have, so the first step is to open the fob and look at the battery itself. The number printed on it tells you what to buy as a replacement.
Key Takeaways
- Most Prius key fobs use a CR2032 or CR2016 coin-cell battery that costs $3 to $8 and is sold at pharmacies, supermarkets, and hardware stores.
- The fob opens by sliding a small metal lever or button on the side, and the battery sits in a plastic holder that you can lift out by hand.
- When you put the new battery in, make sure the flat side faces up toward the fob's cover, not down toward the circuit board.
- If your key fob still does not work after you replace the battery, the problem is likely the fob itself or the car's receiver, not the battery you just installed.
How to open the key fob
Look at the side edge of your Prius key fob for a small slot or a raised button. On most models, you will see a thin metal lever or a plastic tab on one of the long sides. This is the release mechanism.
Insert a coin (a dime or penny works) into the slot, or press the tab with your thumb, and slide or twist gently. The fob will separate into two halves — the plastic cover and the circuit board underneath. Do not force it; if it does not give after gentle pressure, you are probably pushing in the wrong spot. Try the other long edge.
Once the fob is open, you will see the battery sitting in a small plastic holder or tray. It is a flat, round disc, usually silver or gold colored.
Identifying the correct replacement battery
Look at the top surface of the battery that is currently in your fob. You will see a number printed on it — this is the battery type. Write it down or take a photo with your phone so you have it when you go to the store.
CR2032 is the most common battery for Prius key fobs, but some models use CR2016 or CR2025. Do not guess — buy the exact type printed on your old battery. Coin-cell batteries are inexpensive and widely stocked, so you should find your type at any pharmacy, supermarket, or drugstore. Some hardware stores and big-box retailers also carry them in the electronics section.
Removing the old battery and installing the new one
With the fob open, gently lift the old battery out of its plastic holder. It should come free with light pressure from your fingernail or a plastic tool — do not use a metal screwdriver, which can damage the circuit board underneath.
Before you install the new battery, look at which side is facing up. The flat side with the printed number should face up, toward the fob's cover. The other side (the positive terminal) should face down, toward the circuit board. This is the correct orientation for a coin-cell battery in a key fob.
Place the new battery into the holder with the flat side up, and press gently until it sits flat. You should hear or feel a small click as it settles into place.
Closing the fob and testing it
Align the two halves of the fob so the edges line up evenly. Press them together firmly until you hear a click or feel them snap into place. The fob should feel solid and not have any gaps or loose parts.
Stand near your Prius and press the lock or unlock button on the fob. You should see the car's lights flash or hear the locks respond. If the fob works, you are done. If it does not, try pressing the button several more times — sometimes a new battery needs a moment to make full contact.
What to do if the fob still does not work
If the car does not respond after you have replaced the battery and closed the fob, the problem is not the battery you just installed. The issue is either the fob's circuit board or the receiver inside the car.
Try using your spare key fob if you have one. If the spare works, your original fob is damaged and will need to be replaced. If neither fob works, the car's receiver may need attention — this is a dealer-level repair. If only one fob stopped working and your spare works fine, you know the battery replacement was done correctly and the fob itself has failed.
Storing old batteries safely
Do not throw the old battery in the trash. Coin-cell batteries contain materials that should not go to a landfill. Many pharmacies and supermarkets have battery recycling bins near the customer service desk or in the electronics section — ask an employee where yours is located. Some communities also have hazardous waste collection days where you can drop off batteries for free.
Recycling keeps these materials out of the environment and allows them to be reused in new products. It takes just a moment to drop off your old battery, and most places make it convenient by having bins in straightforward-to-reach locations.
Frequently Asked Questions
Can I use a different battery type if I cannot find the exact one?
No. Different coin-cell batteries have different voltages and sizes. Using the wrong type can damage the fob's circuit board or not fit in the holder at all. Buy the exact type printed on your old battery.
How often do I need to replace the battery?
Most key fob batteries last two to four years with normal use. If you use your fob frequently, it may need replacement sooner. You will notice the fob becoming less responsive — the car takes longer to unlock, or you have to press the button multiple times.
What if I drop the battery or lose it while the fob is open?
Coin-cell batteries are small and straightforward to lose. If this happens, do not close the fob without the battery inside — you could damage the circuit board. Go back to the store and buy a replacement, then install it before reassembling the fob.
Is it safe to handle the battery with my bare hands?
Yes. Coin-cell batteries are safe to touch. Avoid touching the flat surfaces directly if you can, since skin oils can affect the connection, but brief contact with your fingers will not hurt the battery or the fob.
Do I need to reprogram my key fob after replacing the battery?
No. Replacing the battery does not erase any programming. Once you install the new battery and close the fob, it should work when ready without any additional steps.