Most key fob batteries take five minutes to replace at home
You can change a key fob battery yourself without tools or a trip to a dealer. The battery compartment usually opens with a coin or your fingernail, the old battery slides or pops out, and a new one slides in. The whole job takes longer to find your coin than to do the work. You will need to know your fob's battery type — printed on the old battery itself — and buy a replacement at a drugstore, supermarket, or hardware store for two to five dollars.
Most key fobs use coin-cell batteries: CR2032, CR2025, or CR2016 are the most common. Some fobs hold two batteries instead of one. A few luxury or specialty fobs use different types, but the replacement process is identical. If you are unsure which battery your fob needs, open it first and read the number stamped on the old battery.
Key Takeaways
- Open the fob by sliding a coin into the seam or prying gently with your fingernail — no screwdriver needed for most models.
- The battery type is printed on the old battery itself; write it down before you leave home to buy a replacement.
- Slide the old battery out, note which side faces up, and slide the new battery in the same way.
- Close the fob, test the buttons, and dispose of the old battery at a drugstore or electronics recycler, not in the trash.
How to open the fob without damaging it
Look for a seam running around the edge of your fob. Most fobs split into two halves along this seam. Slide a coin — a dime or penny works — into the seam and twist gently. You should feel the two halves separate slightly. Once the gap opens, use your fingernail or the coin to pry the halves apart the rest of the way.
If your fob has a button on the back labeled "open" or a small slot, press or slide that instead. Some fobs have a screw on the back; if yours does, use a small Phillips or flathead screwdriver to remove it. Do not force the seam if it will not budge — you may have a screw you missed, or the fob may open a different way. Check your vehicle's manual or search online for your specific fob model number.
Once the fob is open, you will see the battery sitting in a small metal or plastic holder. It is usually held in place by nothing — it straightforward rests in the compartment — though some fobs have a small metal clip over the battery.
Removing and replacing the battery
If the battery has a metal clip over it, lift the clip gently and the battery will pop out. If there is no clip, slide the battery out with your fingernail or a coin. Look at which side of the battery was facing up — the side with the + symbol or the flat side — and remember this before you touch anything else.
Take the old battery with you when you shop so you can match the type number exactly. The number is stamped on the flat side of the battery. Buy a fresh battery of the same type and slide it into the compartment with the same side facing up as the old one. If you put it in backward, the fob will not work, but you can straightforward flip it over — it will not damage anything.
If your fob held two batteries, remove and replace both. They are usually the same type, but check both before you buy.
Closing the fob and testing it
Press the two halves of the fob back together until you hear or feel a click. If your fob had a screw, replace it now. Do not overtighten — hand-tight is enough.
Test the buttons right away. Press the lock and unlock buttons a few times to make sure they work. If nothing happens, open the fob again and check that the battery is facing the right direction. Flip it over and test again. If the fob still does not work after you have tried both directions, the new battery may be defective — try a different one, or the fob itself may need repair.
Where to buy a replacement battery
Coin-cell batteries are sold at drugstores, supermarkets, hardware stores, and online retailers. CVS, Walgreens, Target, and Walmart all stock CR2032 and CR2025 batteries in their pharmacy or electronics sections. A single battery usually costs two to five dollars. Buying a pack of two or four costs only slightly more per battery and is useful if you have multiple fobs or devices that need batteries.
You can also order batteries online from Amazon or the manufacturer's website, but this takes several days. For an when ready replacement, a local store is faster and cheaper than shipping.
Disposing of the old battery safely
Do not throw the old battery in the trash. Coin-cell batteries contain lithium or alkaline chemicals that can leak in a landfill. Take the old battery to a drugstore, supermarket, or electronics retailer — most have a battery recycling bin near the checkout or customer service desk. Some hardware stores and Best Buy locations also accept batteries for free recycling.
If you cannot find a recycling bin nearby, call your local waste management office or search Earth911.com to find a recycling center that accepts batteries in your area.
What to do if the fob still does not work
If you have replaced the battery and tested both directions and the fob still does not work, the problem is usually not the battery. The buttons may be worn out, the circuit board may be damaged, or water may have gotten inside the fob. In this case, you have two options: buy a replacement fob from your car dealer or a third-party seller, or have a locksmith reprogram an aftermarket fob to your vehicle.
Dealer fobs are more expensive — usually fifty to two hundred dollars depending on the vehicle — but are may provide to work. Aftermarket fobs cost twenty to sixty dollars and work with most vehicles, though some luxury brands do not accept them. A locksmith can reprogram either type, usually for fifty to one hundred dollars. Before you pay for a new fob, confirm with your dealer or a locksmith that your vehicle can accept an aftermarket fob, because some cannot.
Frequently Asked Questions
Can I use a different battery type if I cannot find the exact one?
No. Different coin-cell batteries have different voltages and sizes. Using the wrong type can damage the fob's circuit board or cause the buttons to work intermittently. Buy the exact type printed on your old battery.
How often do key fob batteries need to be replaced?
Most coin-cell batteries last three to four years with normal use. If you use your fob heavily — pressing the buttons many times a day — the battery may last only one to two years. You will notice the range getting shorter before the battery dies completely.
What if I lose the battery while I am replacing it?
Coin-cell batteries are small and straightforward to drop. Work over a table or towel so you can see where it lands. If you lose it, you still have the old battery to read the type number from, so you can buy a replacement and try again.
Is it safe to replace the battery if the fob is wet?
Let the fob dry completely for at least 24 hours before opening it. Water inside the fob can damage the circuit board. If the fob has been wet for more than a few hours, drying it may not help — the damage may already be done.