Continental 4N0903028J IGBT Driver Board

The 4N0903028J is an IGBT power driver board (power electronics module) designed for the Continental 48V water-cooled belt starter generator (BSG) used in Audi mild hybrid electric vehicle (MHEV) platforms. It controls the switching of the integrated starter-alternator motor, managing 250A peak current at 48V nominal voltage. The module is mounted directly on the alternator housing and utilizes liquid cooling from the engine coolant circuit for thermal management. This component supersedes earlier revisions 4N0903028E, 4N0903028G, 4N0903028N, and 4N0903028P. It is a critical failure point in the MHEV system; replacement requires software adaptation and coolant bleeding procedures per VAG technical specifications.