How to Change the Battery in Your Car Key Fob

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Like anything else relying on a battery, your car key fob can die—often at the worst time. Thankfully, these batteries are easy to replace.

Newer cars come with a key fob of some sort, whether as a separate device attached to your keyring with buttons to lock and unlock your car, or integrated into the key itself. These fobs send a wireless signal to your car to control it, and they operate on battery power. Though batteries can last anywhere from two to five years or more, if the battery in the fob is weak, you might not be able to get into the car or remotely start it (one of many possible secret uses for your key fob). The good news is, key fob battery replacement is simple. Here’s a step by step guide for how to change the battery in your key fob.

Look for the Battery Type Embossed in the Plastic

On some key fobs, the battery type will be printed on the outside. This way, you can go to the store and select your battery before you need to open up the fob. Three of the most popular brands of key fob batteries are Duracell, Energizer, and Panasonic.

Look for the Seam Where the Halves of the Fob Come Together

holding a key fob, observing the seams of a car key fobAlaina DiGiacomo/rd.com

Most key fobs open in a clamshell fashion, where two halves snap together. There will be a seam where you can split the two halves—sometimes there will even be a notch at that seam. If your car still requires you to put the key in the ignition switch, make sure you don’t hang anything from that keyring other than the fob; the weight of your house keys can wear down the ignition cylinder, which is potentially hazardous.

Gently Pry at the Seam or Notch

prying open a car key fob Alaina DiGiacomo/rd.com

When it comes to how to change the battery in your key fob, you’ll only need one tool. Using a small, thin flat-bladed screwdriver (or, sometimes, a sturdy fingernail), pry apart the two halves gently to open the fob down the middle. Most cars with key fobs and transponder keys won’t let you lock your keys inside the car, but you need to be prepared just in case the worst case happens. (By the way—if you have a habit of losing your keys, this key finder can help you out).

Look at the Battery Orientation (Positive and Negative Ends)

observing car key fob 2023 batteries Alaina DiGiacomo/rd.com

The battery will usually resemble a small coin, be marked with the battery size, and have a plus and minus sign. Note carefully which direction the battery is oriented. Once you’ve purchased a new battery of the same size, it will need to go in the same way.

Pop the Old Battery Out and Place the New Battery in

replacing car key battery while holding open key fob Alaina DiGiacomo/rd.com

Usually, the battery will pop out of its place with the press of a finger—if you’re having trouble, that flat-bladed screwdriver will help. Insert the new battery with the same orientation of plus and minus signs.

Snap Your Key Fob Shut and Test the Fob Function

testing car key fob with new batteryAlaina DiGiacomo/rd.com

Assembly is the reverse of disassembly—snap the fob back together and test out the buttons. Everything should be as good as new!

Now that you know how to change the battery in your key fob, learn about the unusual car features you might not know you have.

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Chris Tonn
Chris Tonn is an automotive and transportation expert with years of work in the automotive manufacturing and service industries, as well as a decade of automotive journalism experience. For RD.com, he covers automotive repair and recreational vehicles.