What is relay theft and how does it actually work?

Most people still picture car theft the old way. A brick through a window, an alarm going off, somebody running. That version has very nearly disappeared, and what replaced it is quieter and far more effective.

If your car key is the kind you keep in your pocket and never press, your car can be driven off your driveway without anybody touching that key. It is called a relay attack, and it takes two people about a minute.

Why your key is the weak point

A keyless key is not passive. It is constantly listening, and when the car asks “are you nearby?”, it answers. That conversation is what lets you walk up to the car and have it unlock without pressing anything.

The trouble is that the conversation does not check how far away the key really is. It only checks that the key answered. That is the gap.

The four steps

One person stands near your front door. They hold a small device that picks up the signal your key is giving off, even from a bowl in the hallway or a coat pocket upstairs. These devices reach further than most people expect, and a UPVC door does very little to stop them.

A second person stands by your car holding another device. The first device relays your key’s signal down the street to the second one.

The car hears what it thinks is your key standing right beside it. So it does exactly what it was designed to do. It unlocks.

They press the start button and drive away. No glass is broken. Nothing is forced. Your factory alarm does not make a sound, because from the car’s point of view nothing is wrong at all.

Why your existing alarm does nothing

This is the part people find hardest to accept, and it is worth being blunt about.

Your factory alarm is listening for a break in. It watches for a door being forced, a window going, the ignition being tampered with. It is good at that job.

A relay attack is not a break in. The car is not being attacked, it is being politely asked to open in a language it already trusts. There is nothing for the alarm to hear.

The car is not being broken into. It is being asked to open, and it says yes.

What actually stops it

There are only really two answers, and they work in different ways.

Stop the car moving. A hidden immobiliser such as an Autowatch Ghost means the engine will not start until a code you chose is entered on buttons the car already has. A thief can relay your key, get in, sit in the driver’s seat, and go absolutely nowhere. This is the layer that keeps the car on your drive.

Know the moment it happens. A Pandora alarm with relay protection watches for exactly this pattern and tells your phone straight away, wherever you are. You find out while somebody is still stood on your driveway rather than at seven the next morning.

Most people we fit for end up with one of the two. Some have both, and sleep better for it.

Things that help but are not enough on their own

A Faraday pouch for your keys is cheap and sensible, and we recommend one. It only works if every single person in the house uses it every single time, which is a lot to ask over years. We have written about that separately.

A steering lock is a visible deterrent and genuinely puts some thieves off. It will not stop somebody who has already decided on your car.

Parking off the road helps. Thieves prefer a car they can reach quickly and leave quickly.

None of these are wasted. They are just not the answer on their own.

Is your car at risk?

The simple test: if you can unlock and start the car with the key still in your pocket, it can be relayed. That covers most cars made in the last ten years or so, and almost every car we get called out to.

If you are not sure, send us the make, model and year and we will tell you straight. We will also tell you if we think you do not need us.