Key Fob 101

Today if you buy a new or relatively new car you can expect it to come with a keyless entry system and a remote to operate that system. The remote is often referred to as a key fob because it is typically carried on a keychain. By definition a key fob refers to anything carried on a keychain for decoration or functionality, but most of the time when that term is used it is referring to the keyless entry remote. They have become just as much of a status symbol as anything else, but knowing exactly how they work can be very useful.

A key fob works like many other basic remote controlled systems. In the remote is a computer chip that creates a very unique code that the receiver is programmed to recognize. You do not need to worry that someone could replicate this code because a standard 40-bit rolling code is choosing from about a trillion possibilities. Also, the code that the system uses is not always the same and the remote and receiver need to be synchronized as a result. This is done upon installation of the keyless entry system so no need to worry about it.

There is one problem that can arise from this basic design. If you push the remote and are not close enough to the car for the receiver to pick up the transmission than the two are no longer synchronized. This problem is resolved very easily because a typical system will have many other codes that it will accept after de-synchronization (usually 256). However, this means that if you press the remote 257 times while not in range of the car you could have a problem because the remote has no acceptable codes left to attempt. In this case you will need to reprogram the system; a process that varies by make and model of the vehicle, but can usually be found online.

Finally, keep in mind that because this technology is so complex, key fobs are not interchangeable and cannot be copied. You need to take good care of that little piece of plastic because if you lose or break it, then a new one will have to be purchased and programmed. This can be a costly process, but again it depends on the kind of car you have. For some vehicles there are just a few quick steps to follow but for others a professional mechanic (with the appropriate equipment) will have to do it. I would recommend checking online to see if you could program a new remote yourself as it will save you about $50-$100.