Physical keys used to be standard, but today’s cars often have a key fob instead, either built into the key or as a separate remote. Of the many uses for your key fob, it can lock, unlock and even start your car—so if the batteries die, you could be stuck in an annoying or even dangerous situation. We’ll show you how to change the battery in your key fob—quickly, safely and without a trip to the dealership.

Reader’s Digest walks you step-by-step through this must-have skill. The good news? Changing the battery in your key fob is easy. If your fob needs a new battery, keep reading to learn exactly what to do to get you back on the road.

Get Reader’s Digest’s Read Up newsletter for more car news, humor, travel, tech and fun facts all week long.

How to change the battery in a key fob

Changing the battery in your key fob just takes a few minutes, and you don’t need complicated tools. Check your owner’s manual if you have any questions, but you’ll likely just need a small flathead screwdriver and a new battery. Here’s what to do:

Look for the battery type on the fob

This is rare, but on some key fobs the battery type is printed on the outside, allowing you to go to the store and buy the correct battery before you open up the fob. If you don’t see the battery type on the outside of the fob, skip to the next step.

Find the seam where the fob comes 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. Find the seam where you can split the two halves, and look for a notch or slot where you can open the fob or insert a tool. Some fobs have a removable key, which can be used to open the fob.

Gently pry open the fob

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

Insert the screwdriver or your key into the slot, opening or seam. Gently pry the two halves apart and open the fob down the middle.

Check the orientation and remove the battery

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

The battery will usually resemble a small coin, be marked with a code and have a plus and a minus sign. Note carefully which way the battery goes in the fob. (If you don’t put the new one in the same way, your fob won’t work.) Remove the battery with your finger, or pop it out with the screwdriver.

Insert the new battery

replacing car key battery while holding open key fob Alaina DiGiacomo/rd.com
The fob will have a plus and minus sign printed inside, letting you know which way the battery goes. Insert the new battery, matching the plus and minus signs. Write down the battery code or save the packaging so you know what to buy next time. Recycle the old battery.

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 the buttons. Everything should be as good as new!

FAQ

How do I know it’s time to change my key fob battery?

Unresponsive buttons, decreased range and a warning light on your dashboard are signs you need to replace your key fob battery. The typical lifespan of a key fob battery is between two to five years, depending on usage and environmental factors.

Will I need to reprogram my key fob after replacing the battery?

Not usually. Most key fobs will continue to work normally after a battery change, but if your fob doesn’t respond it may require reprogramming. Check your owner’s manual or call your dealership for specifics, as this varies by car make and model.

Can I use a generic battery for my key fob?

Yes, as long as it matches the correct size and voltage. Generic batteries can work just as well, but it’s smart to choose a trusted brand to avoid issues with poor contacts or short battery life. Avoid extremely cheap or less reliable off-brand versions.

What should I do if my key fob still doesn’t work after replacing the battery?

Start by making sure the new battery is installed correctly, with the plus and minus signs aligned correctly. Also check for any dirt or corrosion on the contacts inside the fob. If it still doesn’t work, the fob may need to be reprogrammed or replaced. In rare cases, the issue could be with the car’s receiver.

Can I start my car with a dead key fob?

Yes. Key fobs have a radio transmitter inside that sends the start signal to your car, and it will work in close proximity without a battery. Depending on your car’s model, you may need to hold the fob to the start button or to another location within in the car, such as in the console.

Why trust us

At Reader’s Digest, we’re committed to producing high-quality content by writers with expertise and experience in their field in consultation with relevant, qualified experts. We rely on reputable primary sources, including government and professional organizations and academic institutions as well as our writers’ personal experiences where appropriate. We verify all facts and data, back them with credible sourcing and revisit them over time to ensure they remain accurate and up to date. Read more about our team, our contributors and our editorial policies.

Sources