Keyless and relay theft: how a CAN immobiliser stops it
Relay theft beats the key, not the car. A CAN bus immobiliser puts a second barrier in the way, one the thief can't relay or clone.
What keyless theft is, and how an immobiliser stops it
Keyless or relay theft is where a thief captures the signal from a keyless fob inside your home and relays it to the car, which believes the key is present and unlocks and starts. No forced entry, no cut wires, often under a minute on the driveway.
A CAN bus immobiliser breaks that chain. It arms itself when the ignition goes off and blocks the vehicle from being driven until a secret action is taken, a custom PIN entered on the car's own buttons, or a driver tag present. Relaying the fob is no longer enough.
Why the key is the weak point
Modern cars trust the fob. Relay and key-clone attacks exploit that trust without ever touching the key itself, which is why an alarm alone often doesn't help. The answer is a second, independent barrier the thief has no way to capture.
- Relay attack: two thieves extend the fob's signal from your house to the car in seconds.
- Key cloning: the car's key data is copied to start it without the original.
- Silent and fast: no glass broken, no obvious signs, often over in under a minute.
- The fix: a CAN immobiliser that needs something the fob can't provide, a PIN or a tag.
What it protects
A CAN immobiliser suits the vehicles thieves target with relay and clone attacks.
Keyless cars
The keyless-entry models most exposed to relay theft on the driveway.
High-value 4x4s
Range Rover, Defender and similar targets that insurers increasingly require secured.
Vans and pickups
Tools and load make vans a prime target; an immobiliser stops the drive-away.
Fleets
Consistent, PIN or tag protection across a mixed fleet of vehicles.
Layered with tracking
Combine with a ScorpionTrack S5 for immobilisation, alerting and recovery.
Insurance-driven fits
Meet an insurer's security requirement on a high-risk model.
Worried about keyless theft?
Tell us your vehicle and we'll confirm the right immobiliser, on its own or paired with tracking.
Reference
How a CAN immobiliser blocks the theft
It sits on the vehicle network and refuses to let the car move until it sees the right secret.
- 1
Arms at ignition-off
The moment you switch the ignition off, the immobiliser arms itself on the CAN bus. There's nothing to set.
- 2
Blocks the start
A relayed or cloned key unlocks and cranks, but the immobiliser holds the vehicle so it cannot be driven away.
- 3
Needs your secret
The car only releases when a custom PIN is entered on its own buttons, or a paired driver tag is present.
- 4
Raises the alarm
Paired with a ScorpionTrack tracker, an attack alerts our 24/7 monitoring team, who call to check the vehicle is safe.
Which vehicles it fits
The X-Series works with the vehicle's own buttons and network, so it fits a wide range of cars, vans and 4x4s, including the keyless models most exposed to relay theft. Scorpion has designed and built vehicle security in the UK since 1973.
Speak to us with your vehicle and we'll confirm the right immobiliser, on its own or paired with tracking.
The Scorpion X-Series is an invisible CAN bus immobiliser. It talks to the vehicle network, so there's no obvious box to find and no cut wires to bypass. As soon as the ignition is switched off it arms itself automatically, with nothing for the driver to remember.
To move the car you enter a custom PIN using a sequence of the vehicle's own buttons, unique to you, or carry a driver tag that disarms it as you get in. Pair it with a ScorpionTrack S5 and the tag disarms it automatically, while any attack raises an alert with our 24/7 in-house monitoring team.
Often fitted to keyless models such as:
Common questions
What is keyless or relay theft?
It is where thieves capture the signal from a keyless fob inside your home and relay it to the car, which then unlocks and starts as if the key were present. It needs no forced entry and often takes under a minute.
How does a CAN bus immobiliser stop it?
It arms itself when the ignition is switched off and blocks the vehicle from being driven until a custom PIN is entered on the car's buttons, or a driver tag is present. Relaying the fob alone will not move the car.
What is the Scorpion X-Series?
It is an invisible CAN bus immobiliser that connects to the vehicle network, arms automatically at ignition-off and is disarmed by a custom PIN or a driver tag. It can be fitted on its own or paired with a ScorpionTrack tracker.
Do I need to remember to switch it on?
No. The X-Series arms itself automatically every time you turn the ignition off, so there is nothing to set or forget.
Can I combine an immobiliser with a tracker?
Yes. Paired with a ScorpionTrack S5, a driver tag disarms the immobiliser automatically, and any attempted attack raises an alert with our 24/7 in-house monitoring team. Speak to us about the right combination.
Is an immobiliser or a tracker better against keyless theft?
They do different jobs. An immobiliser stops the car being driven away in the first place. A tracker helps locate and recover it if it is taken. Together they cover both prevention and recovery, which is why many owners fit both.
Do I need both an immobiliser and a tracker?
Not always, but they complement each other. An immobiliser is prevention; a tracker with 24/7 monitoring is recovery and alerting. On a high-value or often-targeted vehicle, or where an insurer asks for it, the pair gives the strongest cover.
Will an immobiliser affect my car or its warranty?
A CAN immobiliser connects to the vehicle network rather than cutting into the factory loom, so a professional installation is clean and reversible. Follow the vehicle maker's guidance for any accessory fitment.