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 reason. The good news is that replacing it takes about two minutes and costs between $3 and $8 for the battery itself. You do not need to visit a dealer or call a technician—you can do this at home with a coin.
The battery type depends on which generation Prius you own. Most Prius models from 2004 onward use a CR2032 battery, which is a flat, coin-shaped cell about the size of a dime. Some newer models may use a CR2025 or CR2016, but CR2032 is by far the most common. You can find these batteries at any pharmacy, grocery store, hardware store, or online retailer.
Key Takeaways
- Prius key fobs typically use a CR2032 battery that you can replace yourself in under two minutes with just a coin.
- The battery compartment is accessed by sliding or prying open the fob's case along the seam where the two halves meet.
- Note which side of the battery faces outward before you remove it, because the new battery must go in the same way.
- If your key fob still does not work after replacing the battery, the problem may be a broken button contact or internal damage, which requires professional repair.
What you need to open the fob
Gather a coin—a dime, penny, or quarter works equally well—and your replacement CR2032 battery. That is all. Some key fobs have a small slot or seam on the edge where you can insert the coin; others have a thin line running around the middle of the fob where the two plastic halves meet. Look at your fob closely to find where the seam is.
If you cannot see a clear seam, check the back of the fob. Many Prius fobs have a small indentation or slot on the back edge. This is where you will insert the coin to pry the fob open. Do not force it—if you cannot find the opening, try rotating the fob to look at all sides.
Opening the fob and removing the old battery
Insert your coin into the seam or slot and gently twist or pry. The fob should pop open into two halves. If it does not budge after light pressure, try a different spot along the seam—sometimes the opening is only accessible from one side.
Once the fob is open, you will see the battery sitting in a small circular compartment. Before you touch it, look at which side is facing up. The battery has a flat side and a slightly raised side. The raised side (marked with a plus sign) should be facing up in most Prius fobs. Take a mental note or take a photo so you remember the orientation.
Gently pry the old battery out with your coin or fingernail. It should come out easily. If it is stuck, do not force it—a small amount of corrosion can make it tight, but patient prying will free it.
Installing the new battery
Before you insert the new battery, check that the raised side (the positive side) is facing the same direction as the old battery was. Slide the new CR2032 battery into the compartment with the raised side facing up. It should sit flat and flush with the compartment.
Press gently on the battery to make sure it is seated properly. You should hear or feel a small click as it settles into place. Do not force it—if it does not sit flat, remove it and check that you have the orientation correct.
Closing the fob and testing
Align the two halves of the fob and press them together firmly until they snap shut. You may hear a small click as they lock back into place. Some fobs require you to press along the seam to may support both halves are fully seated.
Test the fob by pressing the lock and unlock buttons from a few feet away from your Prius. The lights should flash and you should hear the locks engage. If the fob works, you are done. If it does not work, try opening the fob again and checking that the battery is seated correctly and facing the right direction.
What to do if the fob still does not work
If replacing the battery does not restore the fob's function, the problem is likely inside the fob itself rather than the battery. The rubber button contacts underneath the buttons can wear out or corrode, or the circuit board can be damaged. These issues require professional repair or fob replacement.
Contact a Toyota dealership or a local automotive locksmith to discuss repair or replacement options. A new OEM (original equipment manufacturer) Prius key fob typically costs between $200 and $400 before programming, though aftermarket fobs are available for less. Some locksmiths can reprogram an existing fob for $50 to $150 if the fob itself is still functional but was not programmed correctly.
Storing your old battery safely
Do not throw the old battery in the trash. CR2032 batteries contain lithium and should be recycled. Most pharmacies and electronics retailers have battery recycling bins near the entrance or customer service desk. You can also check Earth911.com or Call2Recycle.org to find a recycling location near you.
Recycling keeps hazardous materials out of landfills and recovers valuable metals from the battery. It takes the same amount of effort as throwing it away, and most locations are within a short drive of your home.
Frequently Asked Questions
Can I use a different battery size if I cannot find a CR2032?
No. CR2032, CR2025, and CR2016 are different sizes and will not fit properly or make good contact. The CR2032 is the correct size for most Prius models. If your fob uses a different battery, the manual or a quick search for your specific model year will tell you which one.
How long does a new battery last in a Prius key fob?
A CR2032 battery typically lasts three to four years in normal use. If you use your key fob frequently—pressing the buttons multiple times a day—the battery may last closer to two or three years. Leaving the fob in a hot car or exposing it to moisture can shorten battery life.
What if I drop the battery or it gets dirty?
If you drop the battery on a clean floor, it is fine to use. If it is visibly dirty or corroded, wipe it gently with a dry cloth before inserting it. Do not use water or cleaning solutions. If the battery compartment inside the fob looks corroded or has white or green buildup, clean it gently with a dry cotton swab before inserting the new battery.
Do I need to reprogram my key fob after changing the battery?
No. Changing the battery does not erase the fob's programming. Your Prius will recognize it when ready once the new battery is installed and working. Reprogramming is only necessary if you have a new fob or if the fob was previously erased.
Can I change the battery while the fob is still in my car?
Yes, but it is not necessary. You can change the battery anywhere. Just make sure you do not lose the small battery or the fob halves. Working at a table or over a towel is safer than working inside the car, where small parts can fall into crevices.