Abstract: A system, method, and computer program product assist a technician in troubleshooting an aircraft auxiliary power unit (APU). A portable computer is couplable of download the fault data captured in a memory of the ECU. The fault data corresponds to one or more instances of APU failure. The computer is further programmed to compare the fault data to predetermined fault patterns stored in a database. Each record of the database has one of the fault patterns, a corresponding fault indication, and a corresponding service recommendation indication. The computer is further programmed so that when a record in which the fault pattern matches the fault data is found, the corresponding fault indication and service recommendation are retrieved from the database and provided to the technician via the computer's display or other suitable output mechanism.