If you’ve purchased a car in the last 10 years, you’ve likely received a small remote device with your car.
Sometimes, the device is even attached to the key itself. You’ll typically find three buttons on this remote that have the power to unlock the car, lock the car, and unlock the car’s trunk.
This capability is called “keyless entry” because you can unlock your car without using a key. Additionally, there are remotes that even allow you to start the engine without inserting the key into the ignition. Instead, you just need to keep the remote nearby and press the engine start button, and the engine will start automatically.
This is because the receiver in the ignition button will receive the signal from the remote or the keyless entry transmitter. The remote that gives you these capabilities is called a key fob.
Key Fob Basics
A key fob is essentially a radio transmitter that sends a code to the radio receiver inside your car. The controller chip inside the key fob generates a secure code before it is transmitted to the receiver.
The most technical name for this code is the 40-bit rolling code. “40 bits” means that a random code is generated from about one trillion possible codes. A pseudo-random number generator is what creates this number, and there is one of these generators in both the transmitter and the receiver.
Every time you press a button on your remote, the key fob transmits this 40-bit random code and a function code to your car’s receiver. The 40-bit code is the security function, and the function code tells the car the specific function to perform, such as unlocking or locking the doors.
Since the receiver and transmitter are synchronized when a random number is generated, the receiver will recognize the secure code transmitted to it.
This is why if someone else tried to use their key fob to open your car or start your engine, it wouldn’t work because their transmitter is not synchronized with your receiver. Therefore, the receiver will not recognize the number nor perform any function.
In addition to providing keyless access to your car, key fobs also reduce the chances of you locking your keys in your car.
People tend to use their key fobs to lock their doors as much as they do to unlock them. This way, if they forget their keys in the car, the door will still be unlocked.
But in the rare cases where you lock your key fob in the trunk or inside the car but out of reach, you’ll likely need to call your dealer and have them open it, as they are the ones who can generate a new key fob for you.