OBD is a short from on-board diagnostics system. It can test the vehicle exhaust system oxygen sensors and other related parts in use, and thereby prompt the driver to repair in time. United States in 1988, first in California, leaders of the OBD I, and in 1994 regulations implementing the OBD II . Europe is implemented from 2000 after an increase of Euro III OBD functional inspection, known as the EOBD (europe on-board diagnostics), EOBD requirements are not strictly as the OBD II in United States, the two emission limits is not the same. Because of different test cycles,there are not comparable.OBD main function is to monitor actual use of vehicles with emission control components related to the state, including the engine, catalytic converter, oxygen sensors and other components, resulting in deterioration of vehicle emissions when a certain alarm to the driver, and the corresponding fault code and the freeze frame data for storage. OBD is the I / M (inspection / maintenance) system can not be the missing link, in order to avoid the phenomenon of the vehicle alarm, the user is not timely repair of vehicles, the California study and formulate regulations introduced in the emission OBD III, about OBD monitoring system satellite communication link with the infinite, each one in the state register of all vehicle emissions can be real-time understanding of the higher authorities.