Open the key fob by sliding or prying the two halves apart
Most Lexus key fobs split into two plastic halves held together by a small slot or seam. Look for a thin line running around the edge of the fob — that is where the two pieces separate. Insert a flat tool (a coin, flathead screwdriver, or even a butter knife) into the slot and gently twist or pry until you hear a small click. The two halves should slide apart easily; if they resist, try a different spot along the seam rather than forcing it.
Once the fob is open, you will see the circuit board and the battery sitting in a small metal or plastic holder. The battery is usually a coin-cell type, most commonly a CR2032, though some Lexus models use CR2025 or CR2016. Check the number printed on the old battery before you buy a replacement — it matters, because these sizes are not interchangeable.
Key Takeaways
- Lexus key fobs typically use a CR2032 coin-cell battery, but check the number on your old battery before buying a replacement.
- Open the fob by finding the seam around the edge and gently prying with a flat tool until the two halves separate.
- Note which way the battery sits in its holder — the positive side (marked with a + symbol) faces up in most Lexus fobs.
- Replace the old battery with the new one in the same orientation, then snap the two halves back together and test the buttons.
- Coin-cell batteries cost between $3 and $8 and are sold at pharmacies, grocery stores, hardware stores, and online retailers.
Remove the old battery and note its position
The battery sits in a small metal or plastic cradle with two contact points — one on top and one on the bottom. Look at which side is facing up before you remove it. In most Lexus fobs, the positive side (marked with a + symbol) faces upward, but this varies by model year. Take a photo with your phone if you are unsure, because installing the battery backwards will prevent the fob from working.
Gently pry the battery out of its holder using a fingernail or the edge of a plastic tool. Do not use a metal screwdriver or anything sharp that could damage the cradle or the circuit board. Once the old battery is out, set it aside — you do not need to recycle it when ready, but coin-cell batteries should eventually go to a battery recycling program rather than the trash, since they contain small amounts of lithium.
Insert the new battery in the same orientation
Place the new battery into the cradle with the positive side facing the same direction as the old one was facing. The battery should sit flat and snug in the holder. You should not have to force it — if it does not fit easily, double-check that you have the right size battery and that it is oriented correctly.
Once the battery is seated, look at the circuit board to make sure nothing has shifted or come loose. The battery contacts should be clean and making good contact with the battery itself. If you see any corrosion (a white or blue-green crusty buildup) on the contacts, gently wipe them with a dry cloth or a pencil eraser before closing the fob.
Close the fob and test all the buttons
Align the two halves of the fob so the seam is even all the way around, then press them together firmly until you hear a click. The two halves should fit snugly with no gaps. If there is a gap or the fob feels loose, open it again and make sure the battery is seated properly and nothing is blocking the edges.
Test each button on the fob — lock, unlock, panic, and trunk release if your model has one. All buttons should respond when ready when you press them. If a button does not work, open the fob again and check that the battery is making good contact with the cradle. If the fob still does not work after a second battery replacement, the circuit board may be damaged, and you will need to contact a Lexus dealer for a replacement fob.
Where to buy replacement batteries
CR2032 batteries are widely available and inexpensive. You can find them at pharmacies (CVS, Walgreens), grocery stores, hardware stores (Home Depot, Lowe's), and online retailers (Amazon, eBay). A single battery typically costs between $3 and $8, though buying a pack of two or four is often cheaper per battery. Some Lexus dealerships also sell them, but the price is usually higher than retail.
When you buy a battery, check the expiration date on the package. Coin-cell batteries have a shelf life of several years, but an old battery may not hold a full charge. Buy from a retailer with good stock turnover so you know the battery is fresh.
What to do if the fob still does not work after replacing the battery
If you have replaced the battery and tested all the buttons but the fob still does not respond, the problem is likely inside the fob itself rather than the battery. The circuit board may have a cracked solder joint, a corroded contact, or a failed component. Water damage is also common if the fob has been dropped in water or exposed to moisture over time.
At this point, contact your local Lexus dealership and ask for the cost of a replacement fob. Prices vary by model year and region, but a new fob typically costs between $150 and $400 including programming. Some dealerships offer refurbished fobs at a lower price. If your car is still under warranty, the dealer may cover the cost of a replacement fob.
Frequently Asked Questions
Can I use a different size battery if I cannot find a CR2032?
No. CR2032, CR2025, and CR2016 are different sizes and will not work interchangeably. A battery that is too small will rattle in the holder and lose contact; one that is too large will not fit. Always use the exact size printed on your old battery.
What if I drop the battery inside the fob while replacing it?
If the battery falls inside the fob but you can still see it, use a small magnet or a piece of tape on the end of a pencil to fish it out. If it is truly stuck, do not force it — contact a Lexus dealer for help. Forcing the fob open further could damage the circuit board.
Do I need to reprogram the fob after changing the battery?
No. Changing the battery does not erase the fob's programming. As long as the new battery is the correct size and installed in the right direction, the fob should work when ready without any reprogramming.
How often do I need to replace the battery?
Most Lexus key fob batteries last between three and four years with normal use. If you use the fob frequently or live in a humid climate, the battery may wear out sooner. You will notice the buttons becoming less responsive or requiring multiple presses before the fob works.
Is it safe to replace the battery myself, or should I go to a dealer?
Replacing the battery yourself is safe and straightforward. You do not need any special tools or training. A dealer will charge you $20 to $50 for the same job, so doing it at home saves money and takes only a few minutes.