How relay attacks steal keyless cars in under 60 seconds — and the one thing that stops them

A car is stolen in England and Wales every 3 to 4 minutes. In 70% of those thefts, no key was used, no window was broken, and no alarm was triggered. The thieves were in and out in under a minute — and they’ll be long gone before you realise your car is missing.

This isn’t science fiction. This is what’s happening on driveways across the UK every single night. And the frightening part? Factory security — the immobiliser your car came with, the keyless entry system the manufacturer is so proud of — was simply not designed to stop it.

In this article, I’m going to show you exactly how relay attacks work, why they’re almost impossible to detect, and the one mechanical solution that thieves genuinely cannot get around.

What is a relay attack?

A relay attack is a method of car theft that exploits the way keyless entry and keyless start systems work. Your car’s key fob constantly broadcasts a low-power radio signal. When that signal gets close enough to your car, the car recognises it and unlocks — that’s the convenience feature you paid for.

A relay attack amplifies and relays that signal over a much longer distance than it was designed to reach. The thieves don’t need your key. They just need to be near it — even through the walls of your home.

How a relay attack bridges the gap between your key and your car.

How relay attacks work — step by step

Here is what a professional car theft team actually does. This is worth understanding in detail, because once you see how simple it is, you’ll understand why the standard advice — “put your keys in a Faraday pouch” — barely scratches the surface.

“They can be in and out in seconds without a single window being smashed or alarm being triggered. I rushed downstairs and confirmed it was indeed my car that had been stolen. I spent from 10:30pm until 2:30am searching every back street — in complete shock.” — UK car owner, PistonHeads forum

How common is this in the UK?

Relay attacks went from 14% of UK car thefts in 2019 to more than 58% by 2023, according to ABI data. In 2024, insurers paid out £1.24 billion in vehicle theft claims. The technology has become cheap, accessible, and widespread — and it’s accelerating.

The most targeted vehicles are exactly the ones you’d expect: premium and keyless models that attract thieves because of their resale value and the simplicity of the method.

The financial fallout goes well beyond the value of the car. Insurance premiums increase for years after a claim. Your no-claims bonus is gone. And with only 40% of stolen vehicles ever recovered — often damaged or stripped — the emotional cost is significant too.

The device that costs £50 and steals £50,000 cars.

What doesn’t protect you against relay attacks

Before we talk about what works, let’s be clear about what doesn’t — because there’s a lot of genuinely bad advice circulating online.

Faraday pouches and signal-blocking boxes

These work — but only if your key is inside them. If your key is on a hook in the hallway, on a kitchen counter, or in a coat pocket by the door, it’s broadcasting a live signal. Most people who own a Faraday pouch don’t use it consistently. And even if you do, the pouch does nothing once a thief has already gained access using a brief signal window.

Steering wheel locks

A visible deterrent. Experienced thieves will cut through a steering wheel column lock in under 90 seconds. They also make your car less attractive than the neighbour’s — which helps until you live next to someone who’s already taken the advice.

Your factory immobiliser

The immobiliser your car came with was designed to prevent theft without a key. The relay attack doesn’t work without a key — it works by borrowing yours. Factory systems were simply not designed to counter this. They recognise a valid key signal; a relay attack provides one.

Dashcams

Useful for insurance claims. Useless for prevention. A thief who knows what they’re doing will have your car on a transporter within the hour — footage rarely leads to recovery before the car is dismantled or exported.

The one thing that actually stops a relay attack

A physical engine immobiliser that operates independently of the car’s key system.

Here’s the logic: a relay attack makes your car think your key is present. Your car responds by unlocking and allowing the engine to start. If the attacker then presses the start button — the engine starts. Job done.

Unless there’s a second layer of protection that the relay attack knows nothing about. A physical relay immobiliser cuts the engine circuit directly — it has nothing to do with key signals, CAN bus communication, or anything the relay device can intercept or replicate.

A thief can clone your key signal perfectly. They cannot overcome a physical circuit cut. The engine simply won’t start. There’s nothing to hack, nothing to relay, and no signal to amplify.

“3 days after buying a Golf R, I was broken into. They were running out the back door as I came in from work. I had an immobiliser fitted a couple of days later. 3 weeks later they came back — different blokes — and broke in again. But they couldn’t start it. That was the moment I trusted it.” — UK car owner, automotive forum

Why a relay-based immobiliser — not a CAN bus one

Not all immobilisers are equal. There are two fundamentally different types, and the difference matters enormously — both for effectiveness and for what it does to your car’s electronics.

CAN bus immobilisers (like the widely-known Ghost) connect to the vehicle’s ECU communication network. This is the same digital network that controls your dashboard, your engine management system, and dozens of other vehicle systems. Over time, interference on this network can cause diagnostic faults, dashboard warning lights, failed starts, and in some cases put the car into limp mode. We’ve spoken to installers who’ve seen this firsthand — and who’ve switched to LockCar specifically because of it.

Relay-based immobilisers (like every product in the LockCar range) work entirely differently. They cut a physical circuit using a 20A relay — completely independent of the ECU, the CAN bus, and the car’s electronics. There is no communication with the car’s brain. No interference. No diagnostic errors. Ever.

You can read more about the CAN bus vs relay distinction — and why it matters for your car’s long-term health — in our detailed guide: CAN bus vs relay immobiliser: the difference that could cost you £800 →

What to buy — and what to look for

At LockCar, we manufacture every product ourselves — from the PCB to the firmware to the app. That means we understand exactly what’s inside each device, and we can stand behind every installation we do. Here are the products we recommend for different situations.

For individual car owners — the IC3ST

For premium vehicles or wider detection range — the IS357

The ↗ LockCar IS357 (£149) adds a 5-metre proximity tag range, Bluetooth, and support for smartwatch and smart ring as a trust device. Walk up wearing your watch — the car is already disarmed. No codes, no buttons.

For maximum remote control — the ONE Plus

The ↗ LockCar ONE Plus (£199) adds 4G remote access, a live camera feed, GPS+GLONASS tracking, and automatic night-time immobilisation. At 11pm (or whatever time you set), your car locks itself down — automatically, without touching the app. Comparable fleet security systems cost £1,500–2,500 per vehicle. The ONE Plus is £199.

The IC3ST — standalone, app-controlled, and fitted in under an hour at your door.

The installation advantage

One of the most common fears people have about aftermarket security is the installer. Who is this person? Are they qualified? What happens if something goes wrong?

At LockCar, there’s no separation between the manufacturer and the installer. Victor designed the device, built it, and will come to your door to fit it. If anything ever goes wrong — which it won’t, because we know every component — there is one phone number. The person who answers it built your device. That combination doesn’t exist anywhere else in this market at this price.

“You’re not buying a product and then finding someone to fit it. We do everything — one person, one responsibility, one call if you ever need us.” — Victor, founder of LockCar

The bottom line

Relay attacks are not a fringe concern. They’re the dominant method of modern car theft in the UK, and they’re growing. Factory security was never built to stop them. The key fob advice helps — but only if you use it perfectly, every single time.

The only reliable protection is a physical relay immobiliser that operates independently of your car’s key system. It doesn’t matter if a thief relays your key signal perfectly — the engine won’t start because the circuit is physically cut, and the relay device has no way to know that or to overcome it.

If you drive a vehicle worth more than £15,000 — especially a BMW, Range Rover, Mercedes, or any other commonly targeted model — this is not optional protection any more. It’s the minimum standard.