How to Re-sync Your Key Fob to Your Car After a Battery Switch

You wake up, follow your morning routine, then get to your car to go to work. But the key fob refuses to work. At first you think it’s just temporary, but after a couple of attempts, you panic. You’re going to be late for work!

If this horror scenario has happened to you, then you’re in good company. When you replace your fob’s batteries, your key also resets. That happens because the key’s programming is associated with the battery, not the chip. If you’ve ever replaced a battery in your remote control car or toy and it suddenly stopped working, then you know what I’m talking about.

But you’re in luck—re-syncing your key fob for your car is easier than it seems. It’s a matter of following a couple of simple steps that vary depending on your car’s age. Both manual and electronic resets are very easy to do.

In this article, you are going to learn how to reset your key fob so that it works again with your car. You’ll never be late for work again. Well, at least not because your key fob isn’t functioning.

What Happens When You Replace Your Key Fob Batteries?

Usually, switching batteries doesn’t affect the key fob. It should still work just fine. However, if your battery has been dead for a while, replacing it might rewrite the key fob’s programming.

Sometimes, when you replace the batteries in your key fob, the chip inside is erased and all the old programming is gone. Basically, your key fob doesn’t recognize your car anymore, because it’s signaling the wrong car.

Imagine you’re calling a friend to open the door and let you in. But you changed your phone number and your friend doesn’t answer you, because he doesn’t recognize your new number and thinks it’s from an annoying call center. That’s exactly what happens here. Your car is expecting a certain code being broadcasted by your fob, but it gets a completely different one. It’s not recognizing your car anymore.

So, you have to reset the fob so that it can “talk” to your car again.

Editor’s note: This doesn’t happen every time you change your battery. In fact, it’s a rare occurrence. It happens most commonly when you have dead batteries and take a while to replace them.

How to Reset Your Key Fob

The ability to reset the key fob yourself depends on your car model’s, and how old it is. Older cars have a manual key reset, while newer models have an electronic method.

The best way to discover how to reset your key fob is by reading your car’s manual. I know reading manuals has gone out of fashion, but really, they’re a goldmine of information.

Resetting your key fob so it can communicate with your car won’t take longer than a couple of minutes.

Editor’s note: Do you know why the process seems so complicated, and it’s most likely to become progressively more complex in the upcoming year? Because attacks on car remotes are becoming increasingly more common. The more you rely on technology, the easier it is to abuse it and gain access to things you shouldn’t.

On Older Cars

If your car is older than 20 years, then it most likely has a manual key reset

You should easily find out how to do it in the car’s manual, but in case you’ve lost it, here’s how the process looks like in the vast majority of cases:

On older cars, you can do it manually in the car’s fuse box. Take off the cover and look for a fuse labeled “key” or “ignition.” Once you’ve found it, pull it out with a pair of pliers. This will reset your key fob.

However, if you can’t find the fuse box, or if it’s too difficult to get to, then you can also use a metal hanger. Bend the wire hanger so that it touches both of the car’s terminals located under the steering wheel. Once you’ve done that, turn on the ignition and wait for about 20 seconds.

The key fob should be reset by then. The next time you try to start your car, hold down the key fob’s unlock button until the car starts.

On Newer Cars

If your car is newer, then you’ll need to reset the key fob electronically. This can be done by following these simple steps:

  • Get into the driver’s seat
  • “Turn on” the car with your key. You don’t need to actually get it moving, just turning the key so that the car starts and its systems are running is enough.
  • With the key still in the “on” position in your ignition, hold down the “lock” button on your key fob.
  • You should hear a “click” sound after a couple of seconds. Also, your car’s dashboard should light up intermittently to signal success.

Your key fob will be working like new in no time.

If you’re unsure of how to do this or don’t feel comfortable trying it on your own, then take it to a mechanic and have them do it for you.

This process is straightforward and takes only a few minutes, so you shouldn’t be charged too much for it. If you are…pick a more honest mechanic next time.

On Special Models

Some manufacturers—particularly luxury car makers—make it so you need specialized tools, like a computer or diagnostic scanner, to reset the key fob.

Why do they do this?

It’s a way to make sure you can’t reset the key fob on your own and have to go to the dealership for help. Dealerships generally charge a lot of money for this service, so it’s in their best interest to make it difficult for you to do it on your own.

Of course, it’s assumed that money isn’t a problem when you purchase these models. And usually, it’s not. Still, it’s a pretty slimy trick they pull off to siphon more money from their beloved customers. After all you’ve spent on a luxury car, they look for more ways to extract more cash from you.

Unfortunately, there’s no way around this. You’ll have to contact the manufacturer and schedule an appointment to have the key fob reset.

Before purchasing a car, make sure you are ok with this caveat, should you pick a model that uses it. Nobody likes being nickel and dimed at every opportunity, especially when you’ve already splurged on a luxury car model. It feels like you are paying for the privilege of paying more to keep your stuff working.

It’s not a laborious process, but it will take some time and you will have to pay a fee. What we don’t do for our beloved cars!

Are You Sure it’s the Key Fob that’s not Working?

Before you go through the trouble of resetting your key fob, make sure that it’s actually not something else causing the problem. For example, your key fob could be broken.

The first thing you should do is use your backup remote (you have one, right?) and see if the car responds to it. If it does, then the problem is with your key fob and you should continue reading this article. If it doesn’t, then there may be a problem with the car’s receiver and you should take it to a mechanic.

Also, ensure you’re using the right battery type. You can check the type of battery your key fob takes by checking the manufacturer’s website or looking at the back of your key fob.

Are you sure your batteries are installed correctly on your key fob?

Another thing to look for is the terminals inside the fob. They should be completely covered by the battery. If they’re not, then you could have a short on your fob and it needs to be fixed before you can use it again.

But, also clean them if they are dirty. Dirt stops the flow of electricity and will keep your key fob from working.

Sometimes the buttons get stuck and don’t respond to your touch. A new casing should do the trick.


Electronic devices are prone to malfunctions. It’s just the nature of the beast. And, unfortunately, key fobs are no exception. If your key fob isn’t working after replacing the battery, don’t worry! You can fix it yourself easily.

All you need is a few minutes and a little bit of know-how. By following the instructions in this article, you should be able to get your key fob up and running again in no time.

A word of warning before ending. It’s always better to consult your car’s manual before doing anything. While the procedure should be the same for every key fob out there, it’s better to make sure you’re doing the right thing.

Just make sure you have the right tools and that you’re using the right type of battery. And if all else fails, take it to a mechanic. They should be able to help you out in a pinch.

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