The goal of this project is to provide a practical means that could be used for diagnosing malfunctions in the vehicle's engine and ease the task of troubleshooting. The basic concept employed in solving this problem was to build an expert troubleshooting system into microcomputer software. The software, employing valid troubleshooting algorithms and working with input from the maintenance technician or mechanic, would specify the actions the technician should take and what information he should gather and input to the computer. The software would then deduce the source of the malfunction and give appropriate directions to the technician for repairing it.