OBD technology was developed in the 1980s by vehicle manufacturers to help technicians diagnose and service the computerized engine management systems of modern vehicles. A new generation of OBD (often referred to as OBD II) is present on 1996 and newer vehicles. All 1996 and newer vehicles now monitor the same components, use the same type of connector, use the same computer "language" and the same criteria for evaluating the powertrain systems and indicating problems to the driver and the repair technician.
OBD monitors all components that make up the engine management system. It can detect a malfunction or deterioration of these components usually well before the motorist becomes aware of any problem. When a problem that could cause a significant increase in emissions is detected, the OBD system turns on a dashboard warning light to alert the driver of the need to have the vehicle checked by a repair technician.