Method of diagnosing the operating state of a motor vehicle diesel engine

A system for diagnosing the operating state of a motor vehicle diesel engine, the engine comprising a pressure acquisition system associated with each cylinder of the engine to acquire the pressure in that cylinder, a system for acquiring the engine shaft angle adapted to deliver the crankshaft angle of each cylinder, and onboard correction system adapted to correct a predetermined set of malfunctions of the cylinders and the acquisition systems and drifts in the operation of the cylinders, which system comprises:

• analysis means for analyzing the operation of each cylinder and the cylinder pressure and engine shaft angle acquisition systems adapted to identify an operating state of the set comprising each cylinder and the cylinder pressure and engine shaft angle acquisition systems as being either a nominal operating state or one of a set of predetermined malfunctions and drifts based on predetermined characteristics of the signal delivered by the cylinder pressure acquisition system;
• and
• correction means for correcting identified malfunctions and drifts belonging to the predetermined set of malfunctions and drifts that can be corrected by the onboard correction system.