The system of the present invention uses the importance of a piece of malfunctioning equipment, the severity and the confidence level in a diagnosis to determine repair priority of the equipment by obtaining the product (46) of the confidence level (CF), importance (IMP) and severity (SEV). The these variables are determined by expert system rules. The severity is the reciprocal (88) of the time to failure. The importance (44) is the cost to repair the maximum damage when the malfunction continues. A malfunction can affect several pieces of equipment in combination, the severity and importance associated with each piece is combined (70) with the confidence and used to determine the repair priority. When the diagnosis of a malfunction is by malfunctioning sensors, the expected equipment life (40) and the availability (86) of sensors that provide a partial backup are considered in prioritizing sensor as well as equipment repair. When a primary piece of equipment is backed up (100), the effect of both pieces of equipment failing (106) is considered in prioritizing the repair. The system ranks the repair of all possible malfunctions on a common scale. The system gives a complete repair priority picture and allows the cost effectiveness to be maximized.