Immobilisers
Electronic immobilisers are now fitted as standard to most makes and models of new cars, and have been mandatory fitment on all new cars in the UK since 1998 and in Australia since 2001, and 2007 in Canada.
Most systems work in a similar way – a transponder fitted into a keyfob or in the key itself contains a microcircuit with a code that the car checks for whenever anyone attempts to start the car, and if this code does not match the code in the car, then the system blocks both the ignition circuit and the fuel system. Note that this is a separate system from the mechanism and code which deactivates the cars deadlocks and unlocks the doors.
The microcircuit itself does not have an on-board source of power, but is activated by an electromagnetic field generated by the car, which causes current to flow through the circuit and in turm broadcasts the code to the cars Electronic Control Unit (ECU) for recognition.
Early electronic immobilisers had a fixed code that could be copied, but more modern examples have a rotating code, or a calculus based code that has made copying virtually impossible. Because the immobilisers in most modern cars are embedded within the cars ECU and wiring loom rather than aftermarket add ons, they are very difficult to bypass or remove, hence most car crimes on newer vehicles revolve around the thief acquiring the car keys.
Even if your vehicle does not have a standard electronic immobiliser, current aftermarket systems are of a high standard and often include an alarm, and a well worth investing in to help keep your car safe. In the UK, all systems are rated by a government approved independent body called Thatcham that publishes a list of all reviewed and approved systems, including those currently fitted as standard by manufacturers on all cars for sale. You can view this list here: Thatcham Approved Immobilisers.
Finally, many thanks go to Orangewheels.co.uk who supply Audi UK Cars for their free help in compiling this website.