You can change a Lexus key fob battery yourself in about two minutes
Most Lexus key fobs use a coin-cell battery—typically a CR2032 or CR2025—that you can buy at any drugstore or supermarket for a few dollars. The fob itself is designed to open without tools, and the battery slides out once you do. The whole job takes longer to find the right battery than to swap it.
The exact steps depend slightly on which Lexus model you own, because the fob design changed over the years. But the principle is the same: pry the fob open along the seam, note which way the battery sits, remove it, and slide in the new one the same way.
Key Takeaways
- Lexus key fobs almost always use a CR2032 or CR2025 coin-cell battery, available at pharmacies, supermarkets, and hardware stores for $3 to $8.
- The fob opens by prying gently along the seam between the two halves—no screwdriver needed, though a plastic spoon or old credit card works if your fingernail won't grip.
- The battery slides out of a small metal holder; note which side faces up before you remove it, then install the new battery the same way.
- If the fob still does not work after a new battery, the problem is usually a corroded contact or a dead circuit board, not the battery itself.
Identify which battery your fob uses
The easiest way is to open the fob and look at the battery itself. The part number is printed on the top. CR2032 is the most common; CR2025 is slightly thinner but fits the same slot. A few older Lexus models use CR2016, which is even thinner.
If you want to know before you open it, check your owner's manual—it usually lists the battery type in the key fob section. You can also call a Lexus dealership with your model year and they will tell you over the phone. Once you know the type, buy a fresh battery before you start; most stores stock all three types near the watch batteries.
Open the fob without damaging the case
Look at the seam that runs around the edge of the fob, usually between the rubber buttons and the hard plastic back. That seam is where the two halves separate. Slide your fingernail or a thin, flat object—a plastic spoon, old credit card, or plastic pry tool—into the seam and gently twist to pop the halves apart. Do not use a metal screwdriver; it can scratch the plastic or slip and damage the circuit board inside.
Start at one corner and work your way around the seam. You will feel a slight click or give when the clips inside release. Once one side lifts, the other half usually comes free easily. Set both halves on a clean surface so you do not lose the small spring or rubber gasket that may fall out.
Remove and replace the battery
Inside the fob, the battery sits in a small metal holder or clip. Look at which side of the battery faces up—the + (positive) side or the − (negative) side. This matters. Slide the old battery out of the holder, then slide the new battery in the same way, with the same side facing up.
If the battery is stuck, do not force it. A tiny bit of corrosion can make it tight. Gently rock it side to side as you slide it out. If it still will not budge, you may have a corroded contact (see the troubleshooting section below).
Close the fob and test the buttons
Line up the two halves so the seam is even all the way around, then press them together firmly until you hear or feel the clips snap back into place. The fob should close flush with no gaps.
Press each button—lock, unlock, panic, trunk—and listen for the click that means the transmitter is firing. If you hear clicks and the fob worked before, it should work now. If you do not hear anything, move to the troubleshooting section.
What to do if the fob still does not work
A new battery fixes the problem about 90 percent of the time. If it does not, the issue is usually one of three things: the battery is installed upside down, the metal contacts inside are corroded, or the circuit board is dead.
First, open the fob again and double-check that the battery is facing the right way. The + side should be up if the metal clip is on top, or down if the clip is underneath—look at how the old battery sat. If you flipped it, flip it back and test again.
If the battery is correct, look at the metal contacts inside the fob where the battery touches. If they are dark, discolored, or crusty, they are corroded. Clean them gently with a pencil eraser or a cotton swab barely dampened with rubbing alcohol. Let them dry completely before you close the fob and test again.
If the contacts are clean and the battery is the right way around but the fob still does not work, the circuit board inside is likely dead. This is rare in newer Lexus models but more common in fobs that are 10 or more years old. At that point, you will need a replacement fob from a Lexus dealer or a locksmith who programs Lexus keys. A dealer can usually program a new fob in one visit; a locksmith may be faster and less expensive depending on your area.
Where to buy a replacement battery
CR2032 and CR2025 batteries are stocked almost everywhere: pharmacies like CVS and Walgreens, supermarkets, hardware stores, and online retailers. A single battery usually costs $3 to $8. Buy a name brand like Energizer, Duracell, or Panasonic if you can; they last longer than generic versions and are worth the small extra cost.
Some Lexus dealerships sell batteries too, but they charge more—usually $10 to $15 for the same battery. Unless you are already at the dealer for another reason, a pharmacy or supermarket is faster and cheaper.
Frequently Asked Questions
How often do I need to change the battery?
Most Lexus key fob batteries last three to four years with normal use. If you use the fob heavily—pressing the buttons many times a day—it may last only two years. If you use it lightly, it can last five years or longer. There is no set schedule; you change it when the fob stops responding.
Can I use a different battery type if I cannot find the right one?
CR2032, CR2025, and CR2016 are all the same diameter but different thicknesses. CR2032 is thicker than CR2025, which is thicker than CR2016. If your fob uses CR2025 and you install a CR2032, it may fit but the fob case might not close flush. CR2016 is too thin and will rattle. Stick with the correct type; it is straightforward to find.
What if I lose a small part when I open the fob?
The most common piece to lose is a tiny rubber gasket or spring. If you lose it, the fob will still work but may not be water-resistant. If you can see where it came from, try to put it back. If you cannot find it, the fob will still lock and unlock your car; you just lose some weather protection. A Lexus dealer can replace the gasket if it bothers you.
Is it safe to change the battery myself, or should I go to a dealer?
Changing the battery yourself is safe and takes two minutes. There is no risk to you or the car. The only risk is dropping a small part or installing the battery upside down, both of which are straightforward to fix. A dealer will charge you $50 to $100 for the same five-minute job, so doing it yourself saves money and time.