An immobiliser or immobilizer is an electronic device fitted to an automobile which prevents the engine from running unless the correct key (or other token) is present. This prevents the car from being "hot wired" after entry has been achieved.

Immobilisers have been mandatory in all new cars sold in the United Kingdom since 1997 and in Australia since 2001. In Canada, immobilisers are required in all cars assembled on or after September 1, 2007. Early models used a static code in the ignition key (or key fob) which was recognised by an RFID loop around the lock barrel and checked against the vehicle's ECU for a match. If the code is unrecognised, the ECU will not allow fuel to flow and ignition to take place. Later models use rolling codes or advanced cryptography to defeat copying of the code from the key or ECU.

The microcircuit inside the key is activated by a small electromagnetic field which induces current to flow inside the key body, which in turn broadcasts a unique binary code which is read by the automobile's ECU. When the ECU determines that the coded key is both current and valid, the ECU activates the fuel-injection sequence.

In some vehicles, attempts to use an unauthorized or "non-sequenced" key cause the vehicle to activate a timed no-start condition and in some highly advanced systems, even use satellite or mobile phone communication to alert a security firm that an unauthorized attempt was made to code a key.

Coincidentally, this information is often recorded in modern automobile ECUs, which may record many other variables including speed, temperature, driver weight, geographic location, throttle position and yaw angle. This information can be used during insurance investigations, warranty claims or technical troubleshooting.

Add-on immobilisers are available for older cars or vehicles without factory immobilisers. The insurance approval for a self-arming immobiliser is known as "Thatcham 2" after the [ Motor Insurance Repair Research Centre] in Thatcham, Berkshire, England. Approved immobilisers must intercept at least two circuits; typically the low-voltage ignition circuit and the fuel pump circuit. Some may also intercept the low-current starter motor circuit from the key switch to the relay.

Statistics in Australia [ [ CarSafe] ] show that 3 out of 4 vehicle thefts are older cars stolen for joyriding, transport or to commit another crime. Immobilisers are fitted to around 45% of all cars in Australia, but account for only 7% of those cars that are stolen. In many instances, where a vehicle fitted with an immobiliser has been stolen, the thief had access to the original key. Only around 1 in 4 vehicles are stolen by professional thieves. The majority of vehicles are stolen by opportunistic thieves relying on finding older vehicles that have ineffective security or none at all. An engine immobiliser will deter opportunistic thieves.

ee also

*Anti-theft system


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Look at other dictionaries:

  • immobiliser — [ imɔbilize ] v. tr. <conjug. : 1> • 1771; du lat. immobilis « immobile; immeuble » 1 ♦ Dr. Convertir fictivement en immeuble par le procédé de l immobilisation. 2 ♦ Cour. Rendre immobile, maintenir dans l immobilité ou l inactivité. ⇒… …   Encyclopédie Universelle

  • immobiliser — {{/stl 13}}{{stl 7}}[wym. immobilajzer] {{/stl 7}}{{stl 8}}rz. mnż I, D. u, Mc. immobilisererze {{/stl 8}}{{stl 7}} urządzenie odcinające dopływ paliwa i wyłączające zapłon, uniemożliwiając tym samym uruchomienie samochodu przez niepowołane osoby …   Langenscheidt Polski wyjaśnień

  • IMMOBILISER — v. tr. Maintenir dans l’immobilité. Immobiliser un malade. Immobiliser un régiment. Il signifie, par extension, Faire un placement de capitaux qui rend ces capitaux indisponibles. Immobiliser des capitaux dans l’industrie, dans une affaire, dans… …   Dictionnaire de l'Academie Francaise, 8eme edition (1935)

  • IMMOBILISER — v. a. T. de Jurispr. Donner à un effet mobilier la qualité d immeuble, le convertir fictivement en immeuble. Immobiliser des rentes sur l État. IMMOBILISÉ, ÉE. participe, Des rentes immobilisées …   Dictionnaire de l'Academie Francaise, 7eme edition (1835)

  • immobiliser — (i mmo bi li zé) v. a. Terme de jurisprudence. Donner à un effet mobilier la qualité d immeuble. Immobiliser des rentes sur l État. ÉTYMOLOGIE    Im... négatif, et mobiliser …   Dictionnaire de la Langue Française d'Émile Littré

  • immobiliser — noun something or someone that immobilises …   Wiktionary

  • immobiliser — /ɪˈmoʊbəlaɪzə/ (say i mohbuhluyzuh) noun 1. a device or substance that immobilises something or causes it to be inactive. 2. an anti theft mechanism on a motor vehicle which prevents the engine from starting unless the correct key or other… …   Australian English dictionary

  • immobiliser — vt. imobilizî (Albanais). E.: Clouer, Rester …   Dictionnaire Français-Savoyard

  • immobiliser — immobˈilizer or immobˈiliser noun Anything that renders something immobile, esp a device that prevents a motor vehicle from being started without the proper key • • • Main Entry: ↑immobile …   Useful english dictionary

  • immobilisation — [ imɔbilizasjɔ̃ ] n. f. • 1819; de immobiliser 1 ♦ Dr. Attribution à un bien meuble de certains caractères juridiques des immeubles. 2 ♦ Cour. Action de rendre immobile; résultat de cette action. Immobilisation d un membre blessé, d une fracture …   Encyclopédie Universelle

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