The battery in your Mazda CX-5 key fob lasts three to four years, then dies like any other battery

When your key fob stops locking or unlocking the car, the battery is usually dead. You do not need a dealer visit or special tools—you can swap it yourself in about five minutes with a coin and a replacement battery from any drugstore or supermarket.

The CX-5 key fob uses a CR2025 or CR2032 coin cell battery, depending on your model year. Both are common, inexpensive, and sold in the battery aisle of most stores. The fob itself is designed to open from the side, and Mazda does not seal it in a way that requires tools or voids any warranty.

Key Takeaways

  • Mazda CX-5 key fobs use either a CR2025 or CR2032 battery, which you can buy at any pharmacy, grocery store, or hardware store for a few dollars.
  • The fob opens by sliding a coin into the slot on the side and twisting gently—no screwdrivers or prying needed.
  • When you install the new battery, the metal side faces up toward the button, and the flat side faces down.
  • If the fob still does not work after the battery swap, the problem is likely the fob itself, not the battery, and a dealer can diagnose it.

What battery your CX-5 key fob needs

The CR2025 and CR2032 are both 20 millimeters wide and 2.5 millimeters thick (CR2025) or 3.2 millimeters thick (CR2032). They look nearly identical and cost the same. If you are not sure which one your fob uses, buy both—they are cheap enough that it does not matter if you have a spare.

You can find these batteries in the pharmacy section of any grocery store, at drugstores like CVS or Walgreens, at hardware stores, and online. A single battery costs between $2 and $5. Do not buy the cheapest house brand if you can avoid it; mid-range brands like Energizer or Duracell last longer in key fobs.

How to open the key fob

Look at the side of your key fob. You will see a small slot that runs across the edge—this is where the coin goes. The slot is usually on the side opposite the panic button, but check your fob to be sure.

Insert a coin (a dime or penny works fine) into the slot and twist gently, as if you are opening a battery compartment on a toy or remote control. You are not forcing it—just a quarter-turn or so. The fob will split into two halves. Do not pull hard; if it does not budge after a gentle twist, you may have the coin in the wrong spot.

Once the fob opens, you will see the battery sitting in a small metal holder. It is held in place by friction, not glued or screwed down. Gently pry it out with your fingernail or the edge of the coin.

Installing the new battery

Before you put the new battery in, look at which side is which. One side is shiny and domed (the positive terminal), and the other side is flat (the negative terminal). The domed side must face up toward the button of the fob. The flat side goes down into the metal holder.

Slide the new battery into the holder with the domed side up. It should sit snugly and not rattle. Press the two halves of the fob back together until you hear a click. Test the lock and unlock buttons on your car to make sure it works.

What to do if the fob still does not work

If you installed a fresh battery and the fob still will not lock or unlock the car, the problem is not the battery. The fob itself may have water damage, a broken button contact, or a failed circuit board. This is not something you can fix at home.

Take the fob to a Mazda dealer and ask them to test it. They can tell you whether it needs repair or replacement. Some dealers can reprogram a replacement fob on the spot; others may order one. Expect to pay $150 to $400 for a replacement fob, depending on your model year and whether it has a remote start button.

How long the new battery will last

A fresh CR2025 or CR2032 battery in a key fob typically lasts three to four years. Some last longer if you do not use the fob heavily; others wear out faster if you press the buttons many times a day. When the battery dies again, you will go through the same five-minute swap.

If you find yourself replacing the battery more than once a year, the fob may have a small leak or the button contacts may be wearing out. In that case, a replacement fob is more practical than repeated battery changes.

Frequently Asked Questions

Can I use a different battery size if I cannot find a CR2025 or CR2032?

No. Other coin cell batteries may fit the holder but will not make proper contact with the terminals, and the fob will not work. Stick with CR2025 or CR2032. If your store is out of stock, order online or try another store rather than substituting.

What happens if I put the battery in backwards?

The fob will not work, but you will not damage anything. straightforward open it again, flip the battery so the domed side faces up, and close it. No harm done.

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

No. The fob does not need reprogramming after a battery swap. As soon as the new battery is in and the fob is closed, it should work. If it does not, the fob itself has a problem, not a programming issue.

Is it safe to handle the battery with my bare hands?

Yes. Coin cell batteries are safe to touch. You do not need gloves. Just avoid getting them wet or dropping them where they could be swallowed by a child or pet.