Infiniti Nissan Intelligent Key

"Prox" is short for Proximity Remote. A Proximity Remote is simply a vehicle remote that is "detected" as it gets closer to the vehicle. In most cases there are at least three outside antennas, hidden from sight, that can detect a proximity remote as it approaches the vehicle. If the proximity remote is recognized as being valid or registered by the vehicles Body Control Module (B.C.M) computer, it will allow the vehicle to be unlocked or locked by touching a small button located on the outside door handles and rear door / hatch

The Infiniti Nissan name for this system is "Intelligent Key System" or "I - KEY".

Once the proximity remote is moved into the cabin of the vehicle, a different set of antennas detect the proximity remote and will allow the vehicle to be started without using a key.