Key Fob

Security hardware device with built-in authentication used to control and secure access to mobile devices, automobile, computer systems, network services and data. Also known as a hardware token, a key fob provides on-device, one-factor authentication. Key fobs are among a class of physical security tokens that includes smart cards, proximity cards and biometric keyless entry fobs.

Automobile Key Fob

A remote keyless system using a handheld fob. The functions of a remote keyless entry system are contained on a key fob or built into the ignition key handle itself. Buttons are dedicated to locking or unlocking the doors and opening the trunk or tailgate.

Some remote keyless fobs also feature a red panic button which activates the car alarm as a standard feature. Further adding to the convenience, some cars' engines with remote keyless ignition systems can be started by the push of a button on the key fob (useful in cold weather), and convertible tops can be raised and lowered from outside the vehicle while it's parked.

Radio Frequency

Remote keyless entry fobs emit a radio frequency with a designated, distinct digital identity code. Inasmuch as "programming" fobs is a proprietary technical process, it is typically performed by the automobile manufacturer. In general, the procedure is to put the car computer in 'programming mode'.

Programming mode: usually entails engaging the power in the car several times while holding a button or lever. It may also include opening doors, or removing fuses. The procedure varies amongst various makes, models, and years. Once in 'programming mode' one or more of the fob buttons is depressed to send the digital identity code to the car's onboard computer. The computer saves the code and the car is then taken out of programming mode.

On early (1998–2012) keyless entry remotes, the remotes can be individually programmed by the user, by pressing a button on the remote, and starting the vehicle. However, newer (2013+) keyless entry remotes require dealership or locksmith programming via a computer with special software.

Wavelengths between 433 and 92 megahertz are used by the vast majority of systems today. This is due to the fact that this frequency range is more common in different parts of the world. Most modern automobile fobs operate on either 315 MHz or 433 MHz. This is not a range, it is two individual portions of radio spectrum.

• 315 MHz
• 433 MHz

The 433 MHz system has a longer range than 315 MHz most likely due to the European Governments permitting more transmit power on that frequency. NA (North American) models are 315mhz and Export Models are 433mhz.

The 315MHz fobs are the most common. The key operates in a frequency range of 315 Mhz. Only the Abrites ZN002 PROTAG programmer is required to program it. They can be used both to start the car and to operate as remote controls.