OBD systems are present in most cars and light trucks on the road today

On-Board Diagnostic (obd) systems are present in most cars and light trucks on the road today. On-Board Diagnostics refer to the vehicle's self-diagnostic and reporting capability, which the vehicle owner or a repair technician can use to query st atus information for various vehicle subsystems.

The amount of diagnostic information available via OBD has increased since the introduction of on-board vehicle computers in the early 1980s. Modern OBD implementations use a CAN communication port to provide real-time data and a standardized  series of diagnostic trouble codes (DTCs), which identify and remedy malfunctions within the vehicle. In the 1970s and early 1980s, manufacturers began using electronic means to control engine functions and diagnose engine problems. This was primarily to meet EPA emission standards. Through the years, on-board diagnostic systems have become more sophis ticated. OBD-II, a new standard introduced in the mid 1990s, provides almost complete engine control and also monitors parts of the chassis,  body, and accessory devices, as well as the car's diagnostic control network.

The On-Board Diagnostic (OBD) standard defines a minimum set of diagnostic information for passenger cars and light and medium-duty trucks, which must be exchanged with any off-board test equipment.

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