Keychain 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 usually carried on a key ring. By definition, a key fob refers to anything carried on a key ring for decoration or functionality, but most often when that term is used, it refers to the keyless entry remote. They’ve become as much of a status symbol as anything else, but knowing exactly how they work can go a long way.
A key fob works like many other basic remote control systems. Inside the remote is a computer chip that creates a unique code that the receiver is programmed to recognize. You don’t need to worry that someone might replicate this code because a standard 40-bit rolling code is choosing from a trillion possibilities. Also, the code that the system uses is not always the same, and as a result, it is necessary to synchronize the remote and the receiver. This is done after the installation of the keyless entry system, so you don’t need to worry about it.
There is a problem that can arise from this basic design. If you press the remote and you’re not close enough to the car for the receiver to pick up the transmission, the two will no longer be in sync. This problem is solved very easily because a typical system will have many other codes that it will accept after desync (usually 256). However, this means that if you press the remote 257 times while you are not in range of the car, you could have a problem with the remote having no acceptable codes to try. In this case, you will need to reprogram the system; a process that varies by vehicle make and model, but can usually be found online.
Finally, please note that because this technology is so complex, the 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, you’ll have to buy and program a new one. This can be an expensive process, but again it depends on the type of car you have. For some vehicles, there are only a few quick steps to follow, but for others, a professional mechanic (with the proper equipment) will have to do it. I would recommend checking online to see if you can program a new remote yourself as it will save you $50-$100.