FAULT DIAGNOSIS METHOD, FAULT DIAGNOSIS SYSTEM, AND FAULT DIAGNOSIS DEVICE FOR ENGINE

In the present fault diagnosis method and the fault diagnosis system (10) for an engine (16), an external diagnosis device (14): obtains continuous data on the incidences of misfire by misfiring cylinders from the vehicle's (12) side with regard to the actually occurring misfire or past incidences of misfire; detects a misfire pattern, which is to be classified according to the presence of continuous incidences of misfire, on the basis of the continuous data; and narrows down a fault site in accordance with the misfire pattern.