Keyless car theft: how relay attacks work and how to stop them
Thieves use devices that extend a keyless fob's signal and drive off in seconds. UK, European and US data, the new UK law, and simple steps to protect your car.
The car is locked in the driveway, the fob is inside the house, and the vehicle still disappears in under a minute, with no broken glass and no alarm. That is keyless car theft, which uses electronic devices to fool passive entry and push-button start. The UK made possessing or supplying such devices a specific crime in 2026. Here is what the data show and what you can do today.
How does a relay attack work?
A keyless fob constantly emits a short-range signal telling the car its owner is nearby. In a relay attack, one device near the home picks up and boosts that signal and another rebroadcasts it next to the car, which unlocks and starts as if the real key were present. Some variants abuse the diagnostic (OBD) port to program a new key. The key point: your fob never has to leave the house.
How big is the problem?
| Source | Indicator | Figure |
|---|---|---|
| UK Home Office (Met Police estimate) | London vehicle thefts using electronic devices | about 60% |
| UK police recorded crime (YE Sep 2024) | Thefts of a motor vehicle | 132,412 |
| Tracker (Jan–Oct 2025) | Recovered vehicles stolen without keys | 93% |
| ADAC (Germany) | Keyless models adequately protected | about 15% of 800+ |
| NICB (US, 2025) | Vehicle thefts | 659,880 (−23%) |
In the US, the NICB says 2025 thefts hit a historic low, and the Hyundai/Kia share fell from 21% in 2023 to 14% after software updates. Yet an insurer analysis cited by Help Net Security tied slower declines in states such as California to keyless and OBD exploits.
What does the new UK law do?
The Crime and Policing Act 2026 created offences for possessing, importing, making, adapting, supplying or offering an electronic device, such as a signal jammer, for use in vehicle theft. The maximum penalty is five years in prison and/or an unlimited fine.
How can you protect your car?
- Keep the fob away from doors and windows.
- Store it in a signal-blocking pouch and test it: the car should not unlock when you walk up.
- Use a visible steering lock and consider an OBD port lock.
- Ask a trusted installer about a kill switch or extra immobilizer, and a hidden GPS tracker.
- Keep the car's software updated; park in well-lit areas; never leave it running unattended.
If your car is stolen, call the police (911 in the US, 999 in the UK), notify your insurer and tracker provider, and change the password of any connected-car app. More in Protection tips and the Radar; see also how to tell if an AirTag is following you.
来源
- GOV.UK — Crime and Policing Act 2026: serious crime factsheet
- NICB — U.S. Vehicle Thefts Experience Historic Decline (mar/2026)
- Help Net Security — Keyless car theft protection (jun/2026; ADAC, Stichting VbV, Mercury)
- Deeside.com — Keyless car thefts hit 15-year high (dados Tracker, nov/2025)