System for diagnosing the starting of an internal combustion engine

A system for diagnosing the starting of an internal combustion engine is described, comprising internal components of the engine and components for managing the engine functionalities, vehicle batteries to supply power to a starter, a fuel injection system; the method comprising a step of detecting and storing (i) the starting time of the internal combustion engine as a discrete function of a temperature, in order to identify homogeneous time between each other with respect to the temperature, and to calculate (ii) a first tendency on said homogeneous time.