Remote keyless systems come as standard or as an option in 70% of cars made today. They consist of a key fob transmitter or a remote and a receiver in the vehicle. To work, they need a frequency, which is unique to them so they can communicate. Due to the security sensitivity of this system, it is regulated by Government agencies in many countries across the world.
Wireless keys for all cars manufactured or assembled in the United States are registered and regulated by the United States Federal Communications Commission. A unique identifier called FCC ID is given to every wireless device. In the case of a car key fob or remote you will find it behind the device.
When you find this ID, go to the website www.fccid.io and type in the code you see. Scroll down the result page to see the frequency of that key.