You can replace your Mazda CX-5 key fob battery yourself in about five minutes with no tools except a coin
The battery inside your key fob dies like any other battery—usually after three to four years of regular use. When your fob stops locking or unlocking the car from a distance, a dead battery is the most common reason. You do not need a dealer visit or special equipment. A fresh CR2025 battery (the standard size for Mazda CX-5 fobs) costs two to five dollars and slides into place once you open the fob case.
The entire job takes longer to read about than to do. You will use a coin to pry open the fob, swap the old battery for a new one, and snap it shut. This guide walks you through each step and shows you what to watch for so you do not accidentally damage the fob while it is open.
Key Takeaways
- Mazda CX-5 key fobs use a CR2025 battery that you can buy at any drugstore, grocery store, or online retailer for a few dollars.
- Open the fob by inserting a coin (a dime or penny works) into the slot on the side and twisting gently until the case separates into two halves.
- The battery sits in a small metal holder; note which side faces up before you remove it, then place the new battery the same way.
- Snap the two halves back together by hand—do not force them, as they should click into place with light pressure.
- If the fob still does not work after the battery swap, the problem is likely a worn circuit board or water damage inside the case.
What Battery Your Mazda CX-5 Key Fob Uses
Your Mazda CX-5 key fob holds a CR2025 battery, a coin-shaped lithium cell 20 millimeters across and 2.5 millimeters thick. This is one of the most common key fob batteries made, so you will find it everywhere—drugstores, supermarkets, hardware stores, and online. A single battery costs between two and five dollars depending on the brand and where you buy it.
When you go to buy a replacement, look for the CR2025 label on the package. Do not grab a CR2032 (slightly thicker) or CR2016 (slightly thinner) by mistake, as they will not sit properly in the holder. If you are unsure which one you need, bring your old battery with you or show the store clerk a photo of your key fob opened.
How to Open Your Key Fob Without Damaging It
Look at the edge of your key fob and you will see a thin slot running along one side. This is where the two halves of the case meet. Insert a coin—a dime, penny, or quarter all work—into that slot and twist gently, as if you were opening a paint can. You are not trying to force the case apart; you are just creating enough leverage for the two halves to separate.
Turn the coin slowly and feel for the moment when the case starts to give. Once you feel that give, stop twisting and gently pull the two halves apart by hand. If the case does not budge after a few gentle twists, try a different spot along the slot—sometimes one side separates more easily than the other. Never use a screwdriver or knife, as these can slip and scratch the plastic or damage the circuit board inside.
Once the case is open, you will see the battery sitting in a small metal holder in the center. The battery is held in place by the metal tabs on either side of the holder, so it will not fall out when you open the fob. Take a moment to note which side of the battery faces up—the positive side (marked with a plus sign) or the negative side (marked with a minus sign)—because you will need to put the new battery in the same way.
Removing the Old Battery and Installing the New One
Gently pry the old battery out of its metal holder using your fingernail or the edge of a coin. The battery should come out easily with light pressure; if it is stuck, do not force it. Once the old battery is out, inspect the metal holder and the inside of the case for any corrosion (a white or blue-green crusty buildup). If you see corrosion, wipe it away with a dry cloth before you install the new battery.
Take your new CR2025 battery and place it into the holder with the same side facing up as the old battery was. The positive side (plus sign) usually faces up in Mazda fobs, but check your old battery to be sure. Press the battery down gently until it sits flat in the holder and the metal tabs on either side hold it in place. The battery should not move when you gently shake the fob.
Closing the Fob and Testing the Lock
Align the two halves of the case so the edges line up evenly. Press them together by hand with steady, even pressure. You should hear or feel a soft click as the case snaps shut. Do not force the halves together; if they do not want to close, check that the battery is sitting flat and that no plastic is pinched between the halves.
Once the case is closed, test the fob by standing a few feet from your CX-5 and pressing the lock button. You should hear the car lock and see the lights flash. Press the unlock button and listen for the unlock sound. If both buttons work, the battery swap is complete. If the fob still does not work, move on to the troubleshooting section below.
What to Do If the Fob Still Does Not Work After the Battery Swap
A new battery fixes the problem about 90 percent of the time. If your fob is still dead after you have installed a fresh CR2025 battery, the issue is usually one of two things: water damage or a worn circuit board.
Water damage shows up as corrosion inside the case—white, blue-green, or black crusty buildup on the circuit board or metal parts. If you see corrosion, the fob may not recover even with a new battery. A worn circuit board happens when the fob is old or has been dropped many times; the tiny electrical connections inside wear out and stop working. In either case, you will need a replacement fob from a Mazda dealer or a third-party fob programmed to your car. Dealer fobs typically cost sixty to one hundred fifty dollars, while aftermarket fobs run twenty to fifty dollars but require programming at a dealer or by a locksmith.
Common Mistakes to Avoid When Replacing the Battery
The most common mistake is installing the battery upside down. Always check which side of the old battery faced up before you remove it, and put the new battery in the same way. If the fob does not work after you close it, open it again and flip the battery over—this fixes the problem when ready.
The second mistake is forcing the case open or closed. If the case does not want to separate, try a different spot along the slot or use a softer coin. If the halves do not snap together easily, the battery is probably not sitting flat in its holder. Open the fob again, press the battery down firmly, and try closing it once more. Forcing the case can crack the plastic or bend the metal tabs that hold the battery in place.
A third mistake is buying the wrong battery size. CR2032 and CR2016 batteries look similar to the CR2025 but are slightly different thicknesses. They may fit loosely in the holder or not fit at all. Always double-check the label before you buy, and if you are unsure, ask the store clerk or bring your old battery with you.
Frequently Asked Questions
How often do I need to replace the battery in my key fob?
Most Mazda CX-5 key fob batteries last three to four years with normal use. If you use the fob heavily—pressing the buttons many times per day—the battery may wear out in two to three years. If you rarely use the fob, it may last five years or longer. You will know it is time to replace the battery when the fob stops working from your normal distance or when you have to press the button multiple times to get a response.
Can I use a different battery size if I cannot find a CR2025?
No. CR2032 and CR2016 batteries are close in size but not the same thickness, and they will not sit properly in the holder. A loose battery may work intermittently or not at all. Always use a CR2025. If your local store is out of stock, order one online—they ship quickly and cost only a few dollars.
What should I do with the old battery after I remove it?
Lithium batteries like the CR2025 can be recycled. Many drugstores and grocery stores have battery recycling bins near the checkout or customer service desk. You can also take old batteries to an electronics recycling center or a hazardous waste collection event in your area. Do not throw the battery in the trash.
Is it safe to replace the key fob battery myself, or should I go to a dealer?
It is completely safe to replace the battery yourself. The fob contains no dangerous parts, and the battery swap takes five minutes with no special tools. A dealer will charge you fifty to one hundred dollars for the same job. Replacing the battery yourself saves money and time.
Will replacing the battery erase my car's programming or settings?
No. The key fob battery has nothing to do with your car's programming. Swapping the battery will not change any settings, erase your radio presets, or affect how the car runs. The fob will work exactly as it did before once the new battery is installed.