Internal combustion engine i.e. diesel engine, diagnosing method for motor vehicle, involves generating alert indicating failure of recirculation system and alert related to injector when oxide value is not equal to reference value

摘要

The method involves determining (301) fresh air flow and nitrogen oxide (NOx) value for a predetermined operation point defined by rate and torque of an internal combustion engine. The fresh air flow is compared (302) with a reference air flow of a reference point associated with the operation point. An alert indicating possible failure of a recirculation system of exhaust gases and alert relative to an injector are generated (305) when NOx value is not appreciably equal to the reference NOx value.