In locksmith terms
Proximity is the feature that lets a vehicle detect an authorized fob within a short distance and react automatically. When the fob is in range, touching or pulling the door handle unlocks the car, and the start button works because the car can sense the fob inside the cabin. Proximity is usually paired with push-to-start ignition.
The fob broadcasts and answers low-power radio challenges. The car uses antennas in the doors and cabin to judge whether the fob is outside at the handle or inside ready to start. Proximity is a function of the fob and the vehicle's body and immobilizer modules working together.
In plain English
A proximity key is the reason you can walk up with the fob in your bag, grab the handle, and the door just unlocks. The car is quietly looking for your fob the whole time and reacts when it is close enough.
Press nothing, keep the fob on you, and the car handles entry and starting. It feels like the car simply knows you have arrived.
Proximity, remote, and smart key: how they relate
These terms overlap. A remote is the button you press to lock or unlock from a distance. Proximity is the hands-free sensing that happens automatically. A smart key is the modern fob that usually does all of it: remote buttons, proximity entry, and push-to-start. Most newer fobs are smart keys with proximity built in.
Battery and lockout quirks
Because proximity sensing constantly draws power, a weak fob battery often breaks the hands-free function first while the buttons still work for a while. If the car says the key is not detected, try the start button against the marked spot some vehicles have, use the buttons, or replace the battery. The hidden emergency blade still unlocks the door manually if needed. A locksmith can replace a failing fob and pair a new one.
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