Relay theft is now the most common method of car theft in London. Thieves can steal a modern keyless car in under 60 seconds — without touching your keys, breaking a window, or triggering your alarm. Here's exactly how it works and what actually stops it.
🚨 In London, a car is stolen every 8 minutes. The vast majority of modern vehicle thefts use relay attack technology. Standard alarms offer almost no protection against it.
What is Relay Theft?
Relay theft — also called a relay attack — is a technique that exploits the keyless entry systems fitted to most modern cars. Your key fob constantly emits a low-power radio signal that your car is designed to detect when you're nearby. Thieves use a pair of relay devices to amplify and clone that signal, tricking your car into thinking your key is present when it isn't.
How Does a Relay Attack Work? (Step by Step)
Thief 1 approaches your front door
While you're asleep or at home, one thief stands near your front door or window with a relay amplifier device. Your key fob is usually somewhere inside — on a hook, in a bag, on a counter.
The signal is captured and amplified
The relay device picks up your key fob's signal through the wall and amplifies it, extending its range from a few centimetres to 100 metres or more.
Thief 2 transmits the signal to the car
A second thief standing next to your car receives the amplified signal and transmits it to your vehicle. Your car thinks your key is right next to it.
Car unlocks and starts — gone in under 60 seconds
The car unlocks, the thief gets in, presses start, and drives away. No smashed windows, no alarm, no trace. The whole process takes under a minute.
Why London is Especially Vulnerable
London's housing density makes relay theft particularly easy. In terraced streets, your car is often parked within metres of your front door — meaning the thief barely needs to amplify the signal at all. High-value vehicles like BMWs, Range Rovers, Mercedes and Audis are the primary targets, and London has a very high concentration of these vehicles.
Theft rings operate professionally — some have been found with relay equipment worth thousands of pounds and organised distribution networks for stolen vehicles. Cars are often exported within hours of being stolen.
Do Car Alarms Stop Relay Theft?
No. This is the uncomfortable truth. Your car alarm is completely useless against a relay attack. Because the car's own system believes your key is present, it doesn't trigger an alarm. The car unlocks and starts as normal — the alarm has no reason to sound.
Even steering wheel locks only buy minutes — professional thieves carry angle grinders. And Faraday pouches for your keys help, but only work when the key is actually inside them (many people forget).
What Actually Stops Relay Theft?
The only device that fully stops a relay attack is a ghost immobiliser — specifically a CAN BUS immobiliser that requires a secret PIN to start the engine.
Here's why it works: even if thieves relay your key signal perfectly and your car unlocks as if you were there, the engine still won't start without the PIN. The ghost immobiliser sits invisibly inside the CAN bus system — there's nothing for thieves to find, bypass, or cut. They get in, press start, nothing happens. They leave.
✅ A ghost immobiliser is the only device that stops relay theft even when thieves have successfully cloned your key signal. The car simply will not start without the correct PIN.
Other Steps You Can Take
- Faraday pouch — store your keys in one overnight. Cheap and effective as a backup measure (£5-15).
- Park in a garage — if you have one, use it. Thieves prefer quick, open access.
- Steering wheel lock — a visible deterrent. Won't stop professionals but may make them move on.
- CCTV — good for evidence after the fact, does little to prevent theft.
- Ghost immobiliser — the only measure that actually prevents the car being driven away.
Which Cars Are Most at Risk in London?
- BMW 3 Series, 5 Series, X5
- Range Rover Sport, Defender, Evoque
- Mercedes C-Class, E-Class, GLE
- Audi A4, A6, Q5, Q7
- Ford Focus, Fiesta (high volume targets)
- Toyota RAV4, Land Cruiser
If your car has keyless entry and you park on a London street, you are at risk regardless of make or model.
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