Category 1 – Combined alarm and immobiliser
Thatcham Research considers a Category 1 device to be the most complex vehicle protection system. A vehicle alarm of this kind may have advanced features such as perimeter and ignition detection or glass break or tilt sensors, all of which have their own battery supply to set off an alarm when needed.
To be considered for a Category 1 device, a vehicle must have an immobiliser that can kick in without action from the driver and must be able to close down one of two operating systems or control systems that a vehicle needs to start. This could be the ignition circuit or the fuel pump circuit.
Category 2 – Electronic immobiliser
A Category 2 device refers solely to immobiliser devices. Again, the immobiliser must isolate at least two systems required for the vehicle to run.
This kind of device must be able to activate on its own.
Category 2/1 – Alarm upgrade
A device can be given a Category 2/1 system if the vehicle Category 2 immobiliser receives a retrofitted alarm system that meets Category 1 specifications.
Category 3 – Mechanical immobiliser
Whilst a Category 2 immobiliser can work on its own, a Category 3 device is a mechanical device that usually has to be set and unset by the user. The device can be either a permanent fixture to a vehicle or a temporary feature, such as a steering wheel or gearbox lock.
To meet the Thatcham specification, a Category 3 device must again isolate at least one of the operating systems needed for the vehicle to be able to function.
Category 4 – Wheel locking devices
This classification can be awarded to any device that locks the vehicle’s steering wheel, such as locking wheel nuts, but they must be reliable and strong, have a proper key replacement procedure, be traceable and help resist an attempted theft.
Category S5 – Post-theft tracking and recovery
This category of protection should be able to track a vehicle’s location following a theft, but should also be able to immobilise a vehicle by halting key engine functions.
Category 7 and S7 – Stolen vehicle location
Category 7 was new for 2019 and replaced the previous Category 6 and 7 devices. Category S7 devices can immobilise a vehicle, as well as track the location of a stolen vehicle, whereas a Category 7 vehicle can track a vehicle but not immobilise it.