On- board diagnostics (OBD) is an automotive term referring to a vehicle's self-diagnostic and reporting capability. OBD systems give the vehicle owner or repair technician access to the status of the various vehicle subsystems. The amount of diagnostic information available via OBD has varied widely since its introduction in the early 1980s versions of on-board vehicle computers. Early versions of OBD would simply illuminate a malfunction indicator light or "idiot light" if a problem was detected but would not provide any information as to the nature of the problem. Modern OBD implementations use a standardized digital communications port to provide real-time data in addition to a standardized series of diagnostic trouble codes, or DTCs, which allow one to rapidly identify and remedy malfunctions within the vehicle. The character would refer to the sub system. • P00xx – Fuel and air metering and auxiliary emission controls. • P01xx – Fuel and air metering. • P02xx – Fuel and air metering (injector circuit). • P03xx – Ignition system or misfire. • P04xx – Auxiliary emissions controls. • P05xx – Vehicle speed controls and idle control system. • P06xx – Computer output circuit. • P07xx – Transmission. • P08xx – Transmission. The following two characters would refer to the individual fault within each subsystem