Immobiliser

[2] They developed a 3x3 grid of double-contact switches on a panel mounted inside the car so when the ignition switch was activated, current from the battery (or magneto) went to the spark plugs allowing the engine to start, or immobilizing the vehicle and sounding the horn.

[citation needed] 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.

[citation needed] In some vehicles, attempts to use an unauthorised 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 unauthorised attempt was made to code a key.

[citation needed] Coincidentally, this information is often recorded in modern automobile ECUs as part of their on-board diagnostics which may record many other variables including speed, temperature, driver weight, geographic location, throttle position and yaw angle.

[citation needed] Immobilisers have been mandatory in all new cars sold in Germany since 1 January 1998, in the United Kingdom since 1 October 1998, in Finland since 1998, in Australia since 2001.

Lack of immobilizers in many Kia and Hyundai U.S. models after 2010 and before mid-2021 made these cars targets for theft in the early 2020s, especially in Milwaukee County, Wisconsin and Columbus, Ohio.