Definition: 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 a scanner into the vehicle's OBD port under the dashboard 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. See car memory saver.

OBD II
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
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 an invasion of privacy and as of 2021 has not been implemented.

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 port is accessible under the dashboard.

Do It Yourself

Car owners can diagnose their own vehicles with a handheld OBD scanner.

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).