Today's automobiles are complex electronic systems containing dozens of microprocessors and a variety of RF transmitters and receivers. Keeping track of all possible interactions that might result in an EMC problem is a formidable task. The expert system tool being developed by General Motors and the Missouri S&T EMC Laboratory will monitor automotive systems while they are being designed. It will identify design features that are likely to present EMC problems and estimate the magnitude of these problems. In this way potential interference problems can be averted before the first prototypes are built and tested.