A set of experimental and computer simulation methods has been applied to reliability analysis of a newly designed resin transfer molded power electronics module for automotive applications, comprising the glass-fiber epoxy multi-layer PCB, populated with various electronic packages. Evaluation of thermo-mechanical stability, determination of moisture ingress, and testing the adhesion quality between the molding compound and the module PCB have been performed along with investigation of heat transfer paths in the module. The experiments in harsh environments have revealed thermo-mechanical stability and acceptable moisture ingress for the module test samples with relatively large BGA components on the glass-fiber epoxy PCBs of different thickness and different solder mask types. Thermal images of the module have been obtained and the CFD model was created and validated with temperature measurements in power-on tests. Extreme heat dissipation modes have been studied by modeling.