what is passive entry on a car

[DiGage]

Passive entry is a car security and convenience system that allows you to lock and unlock your vehicle without physically using a key fob. As long you have the key fob on your person (in a pocket or purse), the car automatically detects your proximity. To unlock, you simply grab the door handle; to lock, you typically touch a designated spot on the handle as you walk away. This system is also known as a Smart Key System or Keyless Entry.

The core technology relies on a low-frequency radio communication between the car and the key fob. When you are within a certain range (usually 3 to 6 feet), the car sends out a periodic signal. Your key fob, which is powered by a small battery, recognizes this signal and responds with a unique code. The car's computer verifies this code and grants access. This handshake happens in a fraction of a second.

A key benefit is the convenience of keeping your key fob tucked away, which is especially useful when your hands are full with groceries, kids, or luggage. Beyond just the doors, most passive entry systems are paired with a push-button start feature, allowing you to start the engine without inserting a key.

It's important to note a key security consideration: relay attacks. Thieves can use devices to amplify the signal from your key fob inside your house to your car parked outside, tricking the car into thinking the key is present. To mitigate this, use a Faraday pouch (a signal-blocking bag) to store your key fob when at home, or check if your fob has a sleep mode where it stops transmitting after a period of inactivity.

Feature	How It Works	Common Names
Unlocking	Grasp the door handle. Sensors detect the touch and the key's proximity.	Intelligent Access, Touch Sensitive Unlock
Locking	Touch a capacitive area on the door handle (often ridges or a square) after closing all doors.	Walk-Away Locking, Touch Lock
Vehicle Start	Press the ignition button while the key fob is inside the vehicle.	Push Button Start, Keyless Go
Typical Range	3 to 6 feet (1 to 2 meters) for door functions.	Proximity Detection
Security	Encrypted code exchange between the car and key fob.	Rolling Codes, Encrypted Handshake

[AlyssaDella]

It’s the thing where you just walk up to your car and grab the handle, and it unlocks. No fumbling for keys in the rain. To lock it, you just touch the little lines on the handle as you leave. The key just needs to be in your pocket or bag. The real game-changer is the button start—no more searching for the ignition slot. It just makes the whole experience smoother and less of a hassle.

[David]

From a technical standpoint, passive entry uses radio frequency identification (RFID). The vehicle has antennas that emit a low-frequency field. The key fob acts as a transponder, waking up when it enters this field and responding with a unique encrypted code. The body control module (BCM) validates this code before activating the door latches. This system is designed for minimal power drain on the fob's battery, which typically lasts several years before needing replacement.

[DelGenesis]

My main concern was security. I read about thieves using signal amplifiers to steal cars with keyless entry. So I looked into it. The good news is that the codes change every time you use it—it’s not a static signal. But yes, relay attacks are a real threat. My solution was to buy a cheap signal-blocking pouch for my key fob at home. It gives me peace of mind. Also, I always manually check that the car is locked by pulling the handle after I walk away.