How Car Thieves Steal Modern Cars (Relay Attack Explained)

What is a relay attack?

A relay attack uses two devices: one held near your house (where your key sits inside), the other near your car. The first device amplifies your key’s wireless signal, the second relays it to the car. The car thinks the key is present, unlocks, and starts. Total time: under 2 minutes.

How thieves know which car

They drive through neighborhoods scanning houses with a small antenna for any keyless car signal. Higher-value targets (Range Rover, Lexus, Mercedes) are mapped and revisited.

OBD-port flashing

Once inside the car (often via window punch or door bypass), thieves connect a $500-1,500 device to the OBD-II port. The device writes a new master key to the immobilizer in 30-90 seconds. They drive away with a brand-new working key.

The chain explained

1. Scan house for key signal
2. Boost signal to car
3. Car unlocks, starts
4. Some thieves also plug in OBD device to write a permanent key
5. Drive away, swap plates, ship out of country in 24-48 hours

What stops each step

• Step 1-3 stopped by Faraday pouch ($25) or Ghost-II ($1,500) — key signal can’t reach car
• Step 4 stopped by OBD lock ($60-120) — port physically blocked
• All steps stopped by Ghost-II — even with the key, car won’t start without your custom PIN sequence