How to Fix a Key Fob That isn't Working
If your key fob doesn't work, you can fix it by following a few simple steps. First, ensure that it's not your backup remote.
If your backup remote is unable to lock and unlock the doors of your vehicle, it is most likely that the primary remote isn't functioning. The most common causes for key problems with your car remote are issues with the circuitry or battery.
Battery
It is not uncommon to find a battery on a key fob for cars to get worn out. It is fairly easy to replace the battery, however it is important to ensure that you choose the correct type that you can refer to your owner's manual, or contact the manufacturer's dealer to find out what kind of battery you require. It is recommended to inspect the battery compartment with care, as dead batteries sometimes leak caustic chemicals that can harm the remote. If changing the batteries doesn't solve the problem, it may be that there are other issues that require attention by a professional. For example, if buttons seem to be stuck or damaged it could be necessary to take the remote apart and rework its components. You could also try reprogramming the vehicle to recognize the new fob.
Buttons
Key fobs may become dirty and worn-out from repeated use. This is not unusual, but it can cause buttons to stop functioning or require a difficult press to get them to function. This can be extremely frustrating, especially if you are away from home and you need to start your vehicle. Even broken car key repair or worn-out buttons are often fixable with a little time and the tools you already have at home.
First, make sure that the batteries have been correctly placed and that the indentation at the back of the button has been filled. Take the remote apart and inspect the circuit board. Check for indications of rust or other indications that the buttons are worn or damaged. For example there could be conductive paint missing. Use a Q-tip dipped into rubbing alcohol to gently clean any membrane contact that has damaged or has conductive paint missing. Do not rub too vigorously as this can damage the conductive paint and stop the button from firing when it is pressed.
Examine the battery connector's terminals carefully for any loose solder connections. If this is the case, simply reconnecting them may bring back function to the button. The same process can be used to restore function to any other loose connections within the fob.
In the end, if any of the buttons made of rubber that are on the front of the key fob have stopped functioning or require a hard press to work it is likely that the graphite disks on the back of the button are wearing down and need to be replaced. You can do this by rubbing a pen across the disks. This should bring the button back to life.
If none of this is useful, or if the button still does not respond to a hard press It could be because the circuit board has gone bad. It is possible to fix this with a quick clean and re-soldering, but it is ideal to have a spare fob on hand in the event that this method doesn't work for you.
Circuitry
If the key fob buttons function, the circuit board inside your remote may be dirty. This issue can be fixed by a thorough inspection. The most frequent causes of dirty circuit boards is water and broken cases. A broken case can let water and other debris to get into the circuit board, which can cause it to short. Water can also eat through pins and vias, which are the tiny connectors found on the board.
If you are handy enough to open your key fob and aren't afraid of making some mess, we can remove the buttons from their sockets and solder in new ones. It's also worth checking the battery terminal connections. They can get very filthy and if they're not tight enough, the buttons might not work or may even remain in their down position. Soldering the terminals and button's back into place is typically all it takes to restore the key fob that is not working to functioning condition.
Non-Remote transponder chips
The non-remote chips sealed in a sealed case are more durable than remote fobs. However, they are susceptible to breaking in the event of a hole being drilled into them or if a car door handle or lawnmower runs over them. The majority of non-remote transponder chips fail, and this can be blamed on an exploded fuse.
If you're not comfortable opening the key fob, you can take the circuit board off and use a multimeter to verify that the diode is operating correctly. If you're not comfortable doing this, head to your local hardware store or Oreilly's and they'll usually have a radio frequency tester that can determine if the key fob is transmitting a signal.
Programming
Key fobs take many abuses and aren't completely indestructible. They can lose their pairing to the car's receiver due to shock or a low battery, which requires them to be reprogrammed. A professional auto locksmith or dealer can reprogram your key fob to get it working again. If resetting or repairing your keyfob does not work it is possible to replace it.