The battery in your Prius key fob lasts two to four years, and you can replace it yourself in under five minutes with a coin and a fresh battery
Your key fob will start to feel sluggish or stop working altogether when the battery runs low. The good news is that you do not need a dealer or special tools. You need a flathead coin (a penny works), a CR2032 battery (the same size used in many watches and calculators), and about five minutes.
The CR2032 battery costs between $3 and $8 at any drugstore, supermarket, or hardware store. It is the same battery across all Prius model years from 2004 onward. Once you have the battery, the replacement itself is straightforward: pry open the fob, remove the old battery, slide in the new one, and snap it shut.
Key Takeaways
- You need only a CR2032 battery and a coin with a flat edge to replace your Prius key fob battery yourself.
- The battery compartment is on the side of the fob and opens by inserting a coin into the slot and twisting gently.
- The old battery slides out easily once the compartment is open; note which side faces up before you remove it.
- The new CR2032 battery costs $3 to $8 and is available at drugstores, supermarkets, and hardware stores.
Locate the battery compartment on the side of your fob
Hold your Prius key fob in your hand with the buttons facing you. Look at the thin edge on the side—you will see a small slot that runs horizontally across the edge. This slot is where you insert your coin. The slot is usually on the side opposite the panic button, but check both sides if you are unsure.
The slot is shallow and narrow by design. A penny, dime, or quarter all work, but a penny is easiest to grip. Do not use a screwdriver or knife—the slot is not deep enough, and you risk damaging the plastic.
Open the fob by twisting the coin in the slot
Insert the edge of your coin into the slot so it sits flat against the plastic. explore gentle, steady pressure and twist the coin counterclockwise (to the left) as if you were opening a jar. You will feel slight resistance, then a small click as the compartment begins to separate.
Do not force it. If the compartment does not budge after a gentle twist, try the other side of the fob—some models have the slot on the opposite edge. Once you feel the click, stop twisting and gently pry the compartment open with your fingernail or the coin edge.
Remove the old battery and note its position
The battery compartment will now be slightly open. You may see the edge of a small silver disc—that is the battery. Gently slide it out with your fingernail or the edge of the coin. The battery is not glued in, so it should come free with light pressure.
Before you set the old battery down, note which side was facing up. Most CR2032 batteries have a flat positive side (marked with a + symbol) and a slightly domed negative side. The positive side should face up in the compartment. If you forget which way it went, the positive side almost always faces the buttons of the fob.
Insert the new CR2032 battery with the positive side up
Take your new CR2032 battery and check that the positive side (the flat side with the + symbol) is facing up. Slide it into the compartment so it sits flat against the bottom. It should fit snugly but not require force. If it feels tight, you may have the battery upside down—flip it and try again.
Once the battery is in place, you should hear or feel a slight click as it settles into the compartment. The battery will sit flush with the edge of the fob.
Close the compartment and test the fob
Align the compartment edge with the rest of the fob and press down firmly until you hear a click. The compartment should sit flush with the rest of the fob—there should be no gap or overhang. If it does not close all the way, remove the battery, check that it is sitting flat, and try again.
Once the compartment is closed, press each button on the fob several times. The buttons should feel responsive and click cleanly. If the fob still does not respond, remove the compartment again and check that the positive side of the battery is facing up. If it is, the battery may be defective—try a different CR2032 from a different package.
Common mistakes to avoid
The most common error is inserting the battery upside down. If your fob does not work after replacement, open it again and flip the battery. The positive side (marked +) must face up toward the buttons.
Another mistake is forcing the compartment open. The slot is designed for gentle twisting, not prying. If you twist too hard or use a tool that is too thick, you can crack the plastic or strip the slot. A coin is the right tool because it is thin and fits the slot exactly.
Do not assume the old battery is dead just because the fob stopped working. Sometimes the battery is fine but the compartment was not closed all the way, or the battery shifted during use. Before you buy a new battery, open the fob, remove the old battery, clean both sides with a dry cloth, and reinsert it. If that does not work, then replace it.
Frequently Asked Questions
Can I use a different battery size instead of CR2032?
No. The CR2032 is the only size that fits the Prius key fob compartment. Other battery sizes will either be too large to fit or too small to make contact with the terminals. Always use CR2032.
How long does a new CR2032 battery last in a Prius key fob?
A CR2032 battery typically lasts two to four years in a Prius key fob, depending on how often you use the fob. Heavy use—pressing buttons many times per day—will drain the battery faster than light use.
What should I do with the old battery?
CR2032 batteries contain small amounts of lithium and should not go in the trash. Most drugstores and electronics retailers have battery recycling bins near the checkout. You can also check Earth911.com to find a recycling location near you.
Will replacing the battery erase my fob's programming?
No. The battery powers the fob's transmitter but does not store the programming code. Replacing the battery will not affect your fob's ability to unlock or lock your Prius.
My fob still does not work after I replaced the battery. What should I do?
First, open the fob again and confirm the battery is inserted with the positive side facing up. If it is, try a fresh CR2032 from a different package—the battery may be defective. If a new battery does not work, the fob's internal circuitry may be damaged, and you will need a replacement fob from a Toyota dealer or a third-party supplier.