Short answer: most modern cars are stolen without the key – by relaying the signal of a keyless key from inside the house, or by injecting messages into the vehicle network (CAN injection). Factory security alone often does not stop these methods. A hidden aftermarket CAN immobiliser that requires a PIN code or a personal tag adds a step these tools cannot bypass on their own.
How cars are stolen today
Relay attack (keyless entry)
Two devices extend the signal between a keyless key inside the house and the car on the drive. The car "thinks" the key is next to it, unlocks and starts. Thatcham Research security ratings have highlighted keyless entry weaknesses on many models.
CAN injection
Thieves reach vehicle wiring – for example behind a headlight – and send fake messages on the CAN bus that tell the car a valid key is present. Security researcher Ken Tindell documented this method after the theft of a Toyota RAV4 in London in 2023. It works without the key and leaves little visible damage.
Key programming
On some vehicles, a new key can be programmed through the diagnostic socket if the thief gains access to the cabin.
What actually helps
- Keep keyless keys away from doors and windows or in a signal-blocking pouch, and switch off keyless entry if your car allows it.
- A CAN immobiliser – a small unit hidden in the wiring that prevents the engine starting until a PIN is entered on existing buttons (steering wheel, window switches) or a personal tag is present. Because it works on the vehicle network, there are no extra switches for thieves to find.
- OBD port protection – limits key programming through the diagnostic socket.
- GPS tracking – does not stop theft, but helps recovery.
- Visible deterrents – steering locks and wheel locks make the car a slower, less attractive target.
Choosing a CAN immobiliser
- Check that the system supports your exact model and year.
- Ask how the unit is hidden and how the installation is documented.
- Ask what happens at service and MOT – most systems have a service mode.
- Use an installer trained by the manufacturer of the system.
Related services
See vehicle security and Ghost immobiliser installation in the Mansfield and Nottingham area. Ask about your car on WhatsApp.