How to Fix a Key Fob That isn't Working
If your key fob doesn't work A few easy steps can be taken to fix it. The first step is to be sure that it's not the backup remote.
If the backup can lock and unlock your car doors it is most likely an issue with the main remote. The most frequent causes of key malfunctions for car remotes are issues with the circuitry or battery.
Battery
The battery in a key fob can be worn out over time. It is relatively easy to change out batteries, but it is important to ensure you select the correct one that you can refer to your owner's manual or contact the dealer for the manufacturer to find out what kind of battery you need. It is also important to examine the battery compartment, as dead batteries can leak caustic chemicals which can damage the remote. If changing the batteries doesn't solve the issue, it may be that there are other issues that require professional attention. For instance, if buttons seem stuck or damaged, it may be necessary to disassemble the remote and rework its components. You could also try reprogramming the vehicle to recognize the new key fob.
Buttons
Key fobs can get dirty and worn-out from frequent use. This is not atypical, but it can cause buttons to stop working or require a very long press to work. This can be very frustrating particularly when you're away from your home and need to switch on your car. Even malfunctioning or worn-out buttons are often fixable with a little time and the tools you already have at home.
First, ensure that the batteries are up correctly and that the indentation on the back of the button is filled. Take the remote apart and look over the circuit board. Examine for indications of rust or other signs the buttons have been worn or damaged. For example the paint that conducts electricity could be missing. Use a Q-tip dipped into alcohol to gently clean any membrane contact that is worn-out or where conductive paint is missing. Do not rub too vigorously in order to damage the conductive paint and stop the button from firing when pressed.
Check the battery connector's terminals for loose solder connections. Soldering them back to their original position can restore the button's functionality in the event that this is the situation. You can follow the same procedure to restore functionality to any other loose connection within the fob.
If any of the rubber buttons on the front of the keyfob are not working or need to be press extremely hard the graphite disks at the back of the button may have worn out and will require replacement. It is usually done by rubbing a pen over the disks. This should bring the button to life.
If none of this is helpful or if the button does not respond to a hard push, then it may be that the circuit board itself has gone bad. It is possible to fix this by a quick clean and replacing the solder, but it is ideal to have a spare fob on hand in the event that this method fails for you.
emergency car key repair
If the key fob buttons are working the circuit board in your remote may be dirty. A very thorough inspection is often enough to resolve this issue. Broken cases and water are the most common causes of dirty boards. A broken case allows water and other debris to pass through and short out the electronic components. Water can also get through pins and vias, which are small connectors on the board.
If you're able to open your key fob and aren't afraid of making an mess, you can take the buttons out of their sockets and put in new ones. It's also worth checking the connections between the battery terminals. If they are loose, the buttons may not work or even become stuck in their down position. Soldering terminals and buttons back to their original positions is often enough to return a malfunctioning fob to a working condition.
Non-Remote transponder chips
Sealed non-remote transponder chips are more durable than the remote fobs they are contained in, but they can be broken by a hole being that is drilled into them or over by a lawnmower or car door handle. The majority of non-remote transponder chips fail, and this can be attributed to a blown fuse.
If you are not comfortable opening the key fob, you can remove the circuitboard and use a multimeter to check that the diode is functioning properly. If you're not sure with this, visit your local Oreilly or hardware store and utilize their RF frequency tester. This will let you know whether the key fob transmits an RF signal.
Programming
Key fobs are subject to a lot of abuse and aren't indestructible. They can lose their pairing to the receiver in your car due to shock or a low battery, which requires the reprogramming. A professional auto locksmith or main dealer will be able to reprogram your key fob to get it working again. In the event that resetting and fixing your key fob isn't working it could be the time to replace it completely.