This study presents a novel research methodology and approach for diagnosing pertinent failures for power electronic converters. The concept of the generalised connection matrix for a sneak circuit analysis is used in this research. A novel modification to this process shown in this study produces a usable feature that provides unique signatures under fault scenarios and could be used to diagnose faults. The novelty lies in using component currents to form the generalised connection matrix. This study presents the results obtained using data collected from fault scenarios on a hardware set-up for the dc–dc buck converter.