How to Fix a Key Fob That isn't Working
If your key fob doesn't work A few easy steps can fix it. First, make sure that it's not the backup remote.
If the backup can lock and unlock your car door, then there's a likely issue with the primary remote. The most frequent causes of car remote key failure are circuitry or battery issues.
Battery
It is not uncommon for the battery in a key fob for cars to wear out. It is simple to replace the battery. However, it is important that you use the correct type. You can consult the owner's manual or contact the manufacturer to find out the right type. It is also a good idea to examine the battery compartment thoroughly since dead batteries may leak caustic chemicals that can cause damage to the remote. If changing the battery doesn't fix the issue, there may be other issues that require attention from a professional. For example, if buttons seem to be stuck or damaged it could be necessary to take the remote apart and rework its parts. It is also possible to reprogramme the vehicle to recognize the new fob.
Buttons
From repeated use, key fobs could wear out and become dirty. It is not uncommon for buttons to stop working, or to require a hard press to get them working. This can be a hassle particularly when you're away from your home and need to turn on your car. Even broken or damaged buttons can be fixed with a little effort and tools you already have at home.
First, make sure that the batteries have been correctly installed and that the indentation at the back of the button is filled. Open the remote carefully and look over the circuit board. Examine for indications of rust or other signs the buttons have been worn or damaged. For instance, conductive paint may be missing. Use a Q-tip that has been dipped in alcohol to gently clean any membrane contacts that have become worn or have conductive paint missing. Do not rub too vigorously, as this could erode the conductive paint, and block the button from firing when it is pressed.
Check the battery connector's terminals carefully for any loose solder connections. Soldering them back in place can restore the button's functionality if this is the situation. The same method can be used to restore functionality to any other loose connections inside the fob.
If, for instance, any of the buttons made of rubber on the front of the key fob stop functioning or require a difficult press to function it is likely the graphite disks on the back of the button are wearing down and require replacement. This can be done by rubbing a pencil on the disks. This should bring the button back to its original state.
If none of these solutions work, or if you still are unable to get the button to respond when pressed hard, it could be that the circuitry is failing. It is possible to fix this issue by cleaning and re-soldering the button however, you should have a spare in case it doesn't work.
Circuitry
If the keys fob buttons are functioning the circuit board that is inside your remote may be dirty. A very thorough inspection will usually resolve this problem. Water and broken cases are the most common causes of boards that are dirty. A broken case can let water and other debris into the circuit board, causing it to short. Water can also damage pins and connectors on the board, referred to as via's.
If remote key fob repair enough to open up your key fob and don't mind some mess, we can de-solder the buttons and then solder new ones in their place. It's also worth checking the battery terminal connections. They can get very dirty and if they're loose, the buttons might not work or may even remain in their down position. Soldering the terminals, and putting the button back into place is typically all that's needed to return a non-working key fob to working condition.
Non-Remote transponder chips
The non-remote chips sealed in a sealed case are more durable than their remote fobs, but they can be cracked in the event of a hole being drilled into them or in the event that a door handle of a car or lawnmower runs over them. Most of the time non-remote transponder chip malfunctions can be blamed on a blown fuse.
If you're handy enough to open up a sealed non-remote key fob and are willing to put up with the mess, you can take off the circuit board and examine the fuse with a multimeter for proper diode function. If you're not comfortable doing this, visit your local hardware store or Oreilly's, and they will usually have an radio frequency tester that can let you know whether the key fob is transmitting a signal.
Programming
Key fobs take a lot of abuse and aren't completely indestructible. They can lose their pairing with the receiver inside your vehicle due to shocks or a low battery, which calls for reprogramming. A professional auto locksmith or main dealer can reprogram your key fob and get it working again. In the rarer case that resetting and repairing your key fob isn't working it could be the time to replace it all over again.