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on-board diagnostics

See OBD.


(On-Board Diagnostics) A vehicle's electronic troubleshooting system. Dating back to the late 1960s when the first diagnostic computer was employed in a Volkswagen, the OBD system reports trouble codes (DTCs) by plugging in an ODB scanner that reads them.

Initially only used by auto mechanics, today, anyone can plug in a scanner to find out why the Check Engine light is on. Units may only display codes, while others report more information, and some can even predict failure.

Starting in the late 1960s, there were various diagnostic interfaces from Volkswagen, Datsun and General Motors, but in 1991, California required a basic set, loosely referred to as OBD I. However, it was not until 1996 that OBD was standardized for all U.S. vehicles with the OBD II specification.

OBD III has been proposed to report emission failures to a regulatory agency, which requires the owner to have the vehicle serviced before the inspection due date. Very controversial, OBD III is seen as excessive invasion of privacy.

OBD II Connector Type A (12 Volts)
Standardized as the SAE J1962 interface in 1996 for the U.S., a scanner is plugged in to read the codes. This 16-pin socket is accessible under the dashboard.

Do It Yourself
Car owners can diagnose their vehicles with this handheld scanner. After retrieving the data from the OBD port, the unit is plugged into a PC for a report with suggestions and cost estimates. (Image courtesy of Corporation,

Maintenance, Tracking and Wi-Fi
Plugged into the OBD port, T-Mobile's SyncUp sends maintenance notifications in real-time to the user's smartphone. Also used for vehicle tracking, trip history and driving behavior, it can even generate Wi-Fi for passengers (see Wi-Fi hotspot).

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