On-board diagnostics (OBD) refers to the automotive electronic system that provides vehicle self-diagnosis and reporting capabilities for repair technicians. An OBD gives technicians access to subsystem information for the purpose of performance monitoring and analyzing repair needs.
OBD is the standard protocol used across most light-duty vehicles to retrieve vehicle diagnostic information. Information is generated by engine control units (ECUs or engine control modules) within a vehicle. They are like the vehicle’s brain or computers.