The battery in your Prius key fob lasts three to four years before it needs replacing
When your key fob stops locking or unlocking your Prius from a distance, a dead battery is almost always the cause. The good news: replacing it takes about five minutes and costs between $3 and $8 for the battery itself. You do not need to visit a dealer or call a technician.
The battery type depends on which generation Prius you own. Most use a CR2032 coin cell battery, which is the same size used in watches, calculators, and many remote controls. Some older models use a CR1632. You can find either at any drugstore, supermarket, or hardware store in the battery aisle, or order them online.
Key Takeaways
- Prius key fobs use either a CR2032 or CR1632 coin cell battery, both available at drugstores for a few dollars.
- You open the fob by inserting a coin or flat tool into the seam and twisting gently to separate the two halves.
- The battery sits in a metal holder and slides out sideways; note which side faces up before you remove it.
- Insert the new battery with the same side facing up, close the fob, and test the buttons before you put it away.
What you need before you start
Gather a coin (a dime or penny works), a small flathead screwdriver, or a plastic pry tool. You also need the replacement battery. If you are not sure which type your fob uses, check your owner's manual or search online for your specific Prius model year—the manual will list it under "key fob" or "remote control."
Work on a clean, flat surface so the small battery does not roll away if you drop it. A kitchen table or workbench is ideal. Keep the fob away from water and do not force anything; if a part does not move easily, you are likely pushing in the wrong direction.
Opening the key fob case
Look at the edge of your key fob. You will see a thin seam running around the middle where the two plastic halves meet. Insert your coin or screwdriver into this seam on one side, then gently twist it like you are opening a jar. The two halves will separate slightly.
Once you have created a gap, work your way around the seam with the coin, twisting gently at each point. Do not pry hard or you risk cracking the plastic. The fob should come apart into two halves without much force. Set the metal circuit board and battery holder aside on your work surface.
Removing and replacing the battery
The battery sits in a metal holder with two small tabs. Look at which side of the battery faces up—this matters. The side marked with a "+" or a number faces up in most Prius fobs. Slide the battery out sideways by pushing it gently with your finger or a plastic tool. Do not pry it with metal, as you can damage the holder.
Insert the new battery into the holder with the same side facing up as the old one. Slide it in until it sits flat and the metal tabs hold it in place. The battery should not move when you gently shake the circuit board. If it feels loose, remove it and try again—it may be slightly misaligned.
Closing the fob and testing
Line up the two halves of the fob so the seams match. Press them together firmly until you hear or feel a click. The fob should close smoothly without gaps. If it does not close all the way, open it again and check that the circuit board is sitting flat in the bottom half.
Test the lock and unlock buttons before you put the fob away. Stand a few feet from your Prius and press the lock button—your car should lock and the lights should flash. Press unlock and listen for the door locks to open. If the buttons work, you are done. If nothing happens, open the fob again and check that the battery is seated correctly and facing the right direction.
What to do if the fob still does not work
If you installed a new battery and the buttons still do not respond, the problem is not the battery. The circuit board inside the fob may be damaged, or the fob itself may have failed. This happens occasionally with older fobs that have been dropped or exposed to moisture.
Your options are to purchase a replacement key fob (which costs $50 to $150 depending on the model) or to visit a Toyota dealer, who can program a new fob to your car. Some locksmiths also program Prius key fobs for less than a dealer charges. Before you buy a new fob, you can also try cleaning the metal contacts inside the battery holder with a pencil eraser to remove any corrosion, then reinstall the battery and test again.
Storing old batteries safely
Do not throw the old battery in the trash. Coin cell batteries contain lithium and can pose a fire risk in landfills. Most drugstores and retailers that sell batteries also accept used batteries for recycling at no charge—ask at the customer service desk.
You can also search for a battery recycling location near you on the Call2Recycle website, which maintains a directory of drop-off locations by zip code. Many municipal hazardous waste collection events also accept batteries. Taking a few minutes to recycle the old battery keeps it out of the waste stream and is the responsible choice.
Frequently Asked Questions
How do I know if my key fob battery is dead?
The buttons stop working from a distance, though they may work if you hold the fob very close to the car. The car may also respond slowly or inconsistently. A dead battery is the most common cause. If replacing the battery does not fix it, the fob itself may have failed.
Can I use a different battery type if I cannot find the right one?
No. CR2032 and CR1632 are different sizes and voltages. Using the wrong type can damage the circuit board or cause the fob to malfunction. Stick with the type listed in your owner's manual. Both types are widely available and inexpensive.
What if I drop the battery inside the fob while replacing it?
Open the fob again and locate the battery—it will have rolled to one side of the case. Gently shake the fob or use a plastic tool to guide the battery back into the metal holder. If you cannot find it, the battery is likely still inside the case and will fall out when you open it again.
Do I need to reprogram my key fob after changing the battery?
No. Replacing the battery does not erase the programming. Your fob will work exactly as it did before, as long as the new battery is installed correctly and the circuit board is not damaged.