Engine immobilizers are devices that prevent a vehicle from starting unless they receive the correct signal from the driver. The goal of these systems is to reduce car theft.
Engine immobilizer devices isolate the ignition system, the fuel system, the starter engine, or a combination of these systems. In order for a vehicle to start, the device must first receive a signal, which can be communicated in a number of ways:
- Transponder (usually built into original keys)
- Remote key (a handheld device that sends a radio or infrared signal)
- Electronic key
- Coded keypad
- Key switch
Immobilizers penetrate car markets in different ways. For instance, in Australia, since 2001, it has been compulsory for all new vehicles to have an immobilizer device installed that meets the Australian Design Requirements (AS/NZS 4601:1999) that were issued in 1999. The Western Australian government also started subsidizing the aftermarket installation of such devices in 1997 and made such installations required in 1999.
Potter and Thomas (2001) found that engine immobilizers reduced the rate of vehicle theft. In most cases, cars fitted with immobilizers had reduced rates of theft compared with cars not fitted. Immobilizers that met more rigorous standards of security were found to be more effective in reducing thefts. For instance, of the 116,906 vehicles stolen in 2000, 91.2 percent had no immobilizer, 4.9 percent had an immobilizer that did not meet Australian Standards, and 3.9 percent had an immobilizer that met Australian Standards.
The lower rate of theft was demonstrated through multiple analyses looking at different kinds of cars, different kinds of immobilizers, and different jurisdictions.