Some sites, such as AutoExpress, are warning about a method of breaking into vehicles with keyless entry by capturing and relaying the fob's signal.

To quote AutoExpress:

The process criminals use to steal a car via keyless theft – also known as relay theft – is relatively simple. First, they buy a relay amplifier and a relay transmitter; these electronic gizmos can be purchased from the darker corners of the internet.

Next, they identify a house with a nice car parked outside and, by using these gadgets, can detect whether the car features keyless entry and go.

One criminal then stands by the car with his transmitter, while a second waves his amplifier around the perimeter of the house. If the car key is close enough the amplifier will detect its signal, amplify it and send it to the accomplice’s transmitter.

This transmitter then effectively becomes the key, and tricks the car into thinking the real key is nearby, whereupon the thieves are able to open the car, get in and drive away. The whole process can take as little as 60 seconds and can be completed in near silence and as for safety reasons the engine won't just cut out when the key is out of range, there is very little to stop the thieves.

Is keyless theft/relay theft a practical threat for vehicles with fob/keyless entry?

  • 2
    They mention this specific technique at the end of a Snopes article covering the broader topic of remote keyless entry (RKE) systems. It seems that it is indeed possible, but you have to be able to get within "a few feet" of the victim's key... not sure if would work through an exterior wall.
    – CactusCake
    Aug 7, 2018 at 22:11
  • This question seems a bit broad. Relay and (for cheaper models) replay attacks should certainly be possible with vulnerable keyless systems. There are mechanisms the manufacturer and possibly the end user can use to protect against this. You might be interested in this question at sec.SE. I'm not sure if this is a good question here though. It would help if you could find a more concrete claim ("car X is / y % of cars are vulnerable to attack z"), or define what you mean by "practical".
    – tim
    Aug 7, 2018 at 22:18
  • it's perhaps better to ask this on security.stackexchange.com Aug 8, 2018 at 2:51
  • @CactusCake Then wait until the owner goes shopping and leaves his car in a parking lot. Getting close to the key in the supermarket should be doable.
    – FooTheBar
    Aug 8, 2018 at 7:13

1 Answer 1


Is keyless theft/relay theft a practical threat for vehicles with fob/keyless entry?

Are videos demonstrating it happening practical enough?

Police in West Midlands, UK have released footage of criminals stealing a car by relaying a signal from the key inside the home, to the car in the driveway. (CNN)


https://www.youtube.com/watch?v=i38qQsuEYOs (random youtube channel)


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