UniEnergy Technologies Battery » why does my key fob not work after replacing battery? (5 Causes & Solutions)

why does my key fob not work after replacing battery? (5 Causes & Solutions)

I’m sure many of you have had to replace the battery in your dead key Fob. But did you know that something might be wrong if it still doesn’t work after replacing the battery?

In this blog post, I’ll review some things to check if your key Fob needs to be fixed after replacing the battery. This way, you can troubleshoot the problem and get your key fob up and running again!

Why your key Fob isn’t working after you change the battery

1. The buttons may be worn

Worn buttons are one of the factors that cause the malfunctioning of your key Fob. The buttons wearing out is an expected occurrence with your key Fob due to constant usage.

When the buttons on the remote wear out, this creates a gap between the contacts. One of the effective methods to examine the state the buttons are in to see If they are worn out is to press the buttons repeatedly. While pressing these buttons, check for the following common problems:

  • Some buttons or all the buttons don’t work except you press the phone in a certain way.
  • One button isn’t working, while the others are faulty.

Also, another common sign is when the key Fob’s plastic covering falls off, which points to a problem with the car remote. In this case, you could use simple tools to open your car key fob and check for broken contacts or buttons that are not in place.

If, after fixing the insides of the car key fob and still no sign of it working, you might need to get a new key fob.

Another method you can use to verify the cause of your key Fob not working is to test another spare remote, and if the same issue persists, the issue might not be the worn-out keys or a contact problem.

Other solutions you could try if you have worn-out keys are as follows:

  • Replace the housing on the remote
  • Change the car key fob

2. Deprogramming


Another reason why a car key fob fails despite changing the battery might mean that the remote has been reprogrammed. Deprogramming is a situation whereby the computer’s vehicle has been instructed to remove all existing access keys from its access list.

This situation can happen as a result of a combination of buttons pressed on the remote, and this is because certain button combinations help to send a message to the vehicle’s computer to invalidate all existing keys.

Also, it’s important to note that some key fobs are not programmed to a single vehicle. Instead, these types of key fobs have sequences that can change which vehicle they can open, and it’s possible to accidentally switch your car key fob into a secondary key state that is unprogrammed.

To check if your car has this feature, you can check the owner’s manual of the car; if it has that feature, you can also check to see if you could reprogram the keys or do the following:

  • contact a locksmith or consult with your dealership
  • reprogramming

We’ll discuss how to reprogram your key fob below.

3. Your Car Door Locks Are Broken

Sometimes, your fob key isn’t working might have nothing to do with the battery change or your key Fob. In most cases, it might be that your car door is locked, or you might need to fix the car door latches. Essentially, this simply means that the lock is damaged.

One of the ways to see if broken locks are why your key Fob isn’t working is to examine the remote and see if it’s working to open or lock one or more doors. Often, you could have multiple door locks failing at once, but if they begin to fail one by one, this is also another sign that your key Fob is not the culprit.

Another means by which you could verify if the lock or car door handle is the problem is to check for the following issues:

  • The lock isn’t opening or doesn’t open when operated, even with a key
  • The remote opens some doors and not all doors
  • The indicator light flashes to signify that a signal has been sent, but without the door opening
  • Door lock showing signs of movement without thoroughly engaging and disengaging
  • If the door won’t open from the inside or the outside

Solutions to the above problems are car locks and car replacements.

In summary, doors that do not open despite several attempts at manipulation are broken locks. Therefore, it is generally not a good idea to abandon your car door locks as they constitute serious security concerns.

4. Your Vehicles Electrical System May Be Damaged

Your Vehicles Electrical System May Be Damaged

This is another potential reason your key Fob might not work when replacing batteries. When your vehicle’s electrical system is damaged, the key Fob might not work. This usually occurs after servicing the car, during which the dashboard and side panels are removed or reinstalled.

In the process of removing panels during servicing, wires are often exposed. As a result, these wires can be damaged or disconnected accidentally or while being fixed back.

So, if you recently had your car serviced and after that, your key Fob begins to malfunction, check for electrical issues. Other issues that could come up as a result of electrical issues:

  • Car horn issues
  • Lights not turning on


  • Reconnection of wires & replacement of damaged wires

5. Your Key May Be Damaged

Various factors can cause this, like water or scratch marks. If you discover that your key Fob stops working immediately after it falls into the water, is stepped on, or is opened, the key might be damaged.

This differs from a key with worn buttons because, unlike a key with worn buttons, a damaged key will require a replacement, and you might incur additional costs for the replacement.

If the issue with the key only concerns the housing, then partial replacement might be all you need. Other symptoms that show that your key is damaged are as follows:

  • if a spare key works
  • The button isn’t moving
  • The key is broken

There are two possible solutions to a damaged key: replacement of the housing & the full.

How to Correctly Change Your Key Fob Battery.

First, start by removing the old battery. You’ll usually see a small tab or latch that you can press or slide in order to release the old battery. Once it’s out, take a look at the circuit board to see if there’s any corrosion or damage.

If everything looks good, then go ahead and insert the new battery, making sure that the battery terminals are facing the correct sides.

Also, be sure to not accidentally knock the circuit board as this could damage your keyfob and it will need to be replaced. Test the key fob to see if it’s working properly, and if not, consult your manufacturer’s manual for further troubleshooting tips.

How to Reset Your Key Fob

In some cases, you may need to reset your keyfob device. Here are a few simple steps to follow so you can get your key fob working again in no time.

The first step is to make sure the doors on your vehicle are closed. Leaving your car doors open may disrupt the reset process.

Next, turn on your car’s ignition system without turning it on all the way, and make sure the radio is off. This is usually just the first click you hear when you turn your key.

Now, press and hold the lock button on your vehicle. Repeat this step 3 or 4 times.

Once the above steps have been completed, listen for the lock sound. The lock sound signals that the key is in programming mode. Now, hold the lock button on your key fob for 5 seconds.

Finally, test the unlock and lock buttons on your key Fob to ensure that the key has been programmed correctly and all keys are functioning properly. Your key fob should be reprogrammed and ready to go.


You may have replaced the batteries in your key Fob and changed the code so that it works again. But when you try to use it, it still doesn’t work. The problem could be a weak signal from the key Fob itself or because it isn’t programmed correctly.

If you have any questions, you can leave them in the comment section below. In summary, whenever you discover that your key Fob isn’t working after replacing the batteries, here are the most common problems;

  • Broken locks
  • deprogramming
  • Damaged key
  • Electrical issues

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