The battery in your Mazda CX-5 key fob typically lasts three to four years before it needs replacing

You can change it yourself in about two minutes with no tools except a coin or flathead screwdriver. The fob uses a CR2025 or CR2032 coin-cell battery — which one depends on your model year — and costs between $3 and $8 at any pharmacy, grocery store, or hardware retailer. You do not need to visit a dealership or buy a new fob.

The process is the same whether your CX-5 is a 2013 or a 2024: pry open the fob, lift out the old battery, drop in the new one with the positive side facing up, and snap the case closed. If your fob still does not work after the battery swap, the problem is usually a dirty contact or a worn circuit board, not the battery itself.

Key Takeaways

  • Mazda CX-5 key fobs use either a CR2025 or CR2032 battery, both available at drugstores and supermarkets for under $10.
  • You can open the fob with a coin or flathead screwdriver by prying along the seam where the two halves meet.
  • The battery slides out easily once the fob is open; insert the new one with the positive (+) side facing upward.
  • If the fob still does not work after you install a fresh battery, the contacts may be dirty or the circuit board may be damaged.

Finding the seam and opening your fob

Look at the edge of your key fob where the two plastic halves meet. You will see a thin line running around the perimeter. This is the seam you need to pry open. Hold the fob in one hand with the metal key ring facing away from you, and use a coin (a dime or penny works well) or a small flathead screwdriver to gently wedge into that seam.

Start at one corner and work the coin slowly around the edge. Do not force it — the two halves are held together by a plastic clip, not screws, and they will separate with light pressure. Once you feel the clip give, you can usually pull the halves apart by hand. The battery will be sitting in a small metal or plastic holder on the inside of one half.

Removing the old battery and inserting the new one

The battery sits in a shallow cup or holder. It may come out easily, or you may need to use your fingernail or the edge of a coin to gently pry it up. Once it is out, note which side was facing up — this matters for the new battery.

Coin-cell batteries have a flat positive (+) side and a flat negative (−) side. The positive side should face upward, toward the inside of the fob. Slide the new battery into the holder with the positive side up, making sure it sits flat and flush. If it does not sit evenly, remove it and try again — a battery that is tilted or loose will not make good contact.

Closing the fob and testing it

Once the battery is in place, align the two halves of the fob so the seam lines up evenly. Press them together firmly until you hear or feel a click. The plastic clip should snap back into place. Test the fob by pressing each button — the lock, unlock, and panic buttons should all respond when ready.

If the fob still does not work, open it again and check that the battery is sitting flat and that the positive side is facing up. If it is, the problem is likely dirty contacts inside the fob or a damaged circuit board, not the battery. In that case, you may need a replacement fob from a Mazda dealer or a third-party supplier.

Knowing which battery size your CX-5 uses

Most Mazda CX-5 models from 2013 onward use a CR2032 battery, which is the larger of the two common coin-cell sizes. Some earlier models or certain trim levels may use a CR2025, which is slightly thinner. The easiest way to know which one you need is to look at the old battery after you remove it — the size is printed on the flat side.

If you have already thrown away the old battery, you can open the fob and measure the holder, or you can buy a CR2032 first since it is the most common size for Mazda key fobs. If it does not fit, a CR2025 will fit in the same holder but may not make as reliable contact. When in doubt, ask the pharmacist or store clerk which size fits your fob model.

Why your fob might still not work after a new battery

A dead battery is the most common reason a key fob stops responding, but it is not the only one. If you have installed a fresh battery and the fob still does not lock or unlock your car, the problem is usually one of three things: dirty contacts, a worn circuit board, or a broken button.

Dirty contacts are the easiest to fix. Open the fob again and look at the metal contacts inside — they should be shiny. If they look dark or corroded, clean them gently with a dry cotton swab or a pencil eraser. Close the fob and test again. If the buttons still do not work, or if a button feels stuck or mushy, the circuit board or button mechanism is likely damaged and the fob will need to be replaced.

Where to buy a replacement battery

CR2032 and CR2025 batteries are sold at nearly every pharmacy, grocery store, and hardware store in the United States. You will find them in the photo section, the watch battery section, or near the checkout counter. Prices range from $3 to $8 for a single battery, though many stores sell them in multipacks for $5 to $10. Online retailers like Amazon also stock them, but you will pay for shipping unless you have a membership.

If you need the battery when ready, a local pharmacy or supermarket is your fastest option. If you want to stock up or save a few dollars, buying a multipack online or at a warehouse store makes sense. Either way, the battery is inexpensive enough that you can afford to keep a spare in a drawer for the next time your fob dies.

Frequently Asked Questions

Can I use a different battery size if I cannot find the right one?

No. A CR2025 will not fit reliably in a holder designed for a CR2032, and vice versa. Using the wrong size risks poor contact and a fob that works intermittently. Buy the correct size for your model, or ask a store employee to help you identify which one your fob needs.

What if the fob case will not open?

The seam may be stuck due to age or moisture. Try using a flathead screwdriver instead of a coin, and work it slowly around the entire edge rather than forcing it in one spot. If the case is truly stuck, a Mazda dealer can open it for you, though they will charge a service fee.

How long does a new battery last in a key fob?

Most coin-cell batteries last three to four years in a key fob, depending on how often you use the buttons. If you press the buttons dozens of times per day, the battery may wear out faster. If you use the fob only a few times per week, it may last longer.

Do I need to reprogram my key fob after changing the battery?

No. Changing the battery does not erase the fob's programming. Once you install the new battery and close the case, the fob should work when ready without any additional steps.

What should I do with the old battery?

Most pharmacies and retailers that sell batteries will take old ones for recycling at no charge. You can also drop them off at an electronics recycling center or a hazardous waste collection event in your area. Do not throw them in the trash.