OBD On Board Diagnostics – BMW E39 1997 - 2001

OBD On Board Diagnostics – BMW E39 1997 - 2001

OBD II standards were developed by the SAE (Society of Automotive Engineers) and CARB (California Air Resources Board). OED I1 is the second generation of on-board self- diagnostic equipment requirements. These standards were originally mandated for California vehicles. Since 1996 they have been applied toall passengervehicles sold in the United States. On-board diagnostic capabilities are incorporated into the hardware and soflwareof the enginecontrol module (ECM) to monitor virtually every component that can affect vehicle emissions. The OED I1 system works to ensure that emissions remain as clean as possible over the life of the vehicle. Each emission-influencing component is checked by a diagnostic routine (called a monitor) to verify that it is functioning properly. If a problem or malfunction is detected, the diagnostic executive built into the OBD I1 system illuminates a malfunction indicator light (MIL) on the instrument panel. The OBD I1 system also stores diagnostic trouble codes (DTCs) about the detected malfunction in the ECM so that a repair technician can accurately find and fix the problem.