Fault diagnostic method and device

A method for monitoring motor vehicle systems that include mechanical components and at least one control device detects, in a first step, input signals and output signals as quantitative signals that characterize the operating behavior, assigns discrete qualitative values to value intervals of the input signals and output signals, which are established using a particular sequence of threshold values. A change to one of the qualitative values is recognized as an event, and consecutive events are stored as an event sequence. The event sequence is compared with a model of the normal behavior of the motor vehicle system, in particular a model composed of all event sequences of the proper operation of the motor vehicle system. If there is a match, it is assumed that the motor vehicle system is operating properly. If there is no match, erroneous operation is assumed.