Most keyless car thefts across Essex now happen without the thief ever touching your keys, breaking a window, or setting off an alarm. Here's exactly how a relay attack unfolds, and the one thing that reliably stops it.
How a relay attack actually works
- One person stands near your front door with a signal-boosting device, picking up the faint signal your key fob constantly emits — even from inside the house.
- A second person stands by your car with a matching relay device, which rebroadcasts that boosted signal to the vehicle.
- Your car "thinks" the real key is right next to it and unlocks — sometimes even allowing the engine to start.
- The whole process typically takes under a minute, and neither thief needs to touch your key at any point.
This is why cars parked directly outside the house — common across Essex driveways and cul-de-sacs — are particularly exposed.
Why a normal alarm doesn't help
A standard factory alarm is designed to detect forced entry — smashed glass, forced doors. Relay theft doesn't trigger any of that, because as far as the car's systems are concerned, the correct key just walked up to it. The alarm has nothing to react to.
What actually stops it
A hidden CAN BUS immobiliser adds a second, completely separate authentication step that has nothing to do with your key signal at all. Even if a thief successfully relays your key and gets the car unlocked, the engine physically won't run until a secret PIN sequence is entered on your existing buttons — something no relay device can replicate, because it isn't stored or transmitted anywhere near the key.
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Can relay theft happen even with my keys locked inside my house?
Yes — that's the whole point of the attack. The signal booster picks up your key's signal through walls and doors, so the keys never need to leave the house. Distance from the car is the only real barrier, which is why a signal-blocking pouch helps but isn't foolproof on its own.
Does a steering lock stop relay theft?
It slows a thief down but doesn't stop the car being started and driven off before the lock is even needed, in a lot of cases. A hidden immobiliser stops the engine from running at all, regardless of whether the key signal was cloned.
Are certain areas of Essex targeted more than others?
Keyless car theft tends to follow wherever higher-value, keyless-entry vehicles are common — commuter towns near the A12, A127 and M25 corridor typically see more of this than rural areas, simply because of vehicle density, not because thieves specifically target one town over another.