Fehlerdiagnosevorrichtung für ein Abgasrückführungssystem einer Brennkraftmaschine

摘要

This invention relates to a trouble diagnosis device for an exhaust gas recirculation (EGR) of an internal combustion engine. In the condition that an EGR control valve is turned on and off according to whether or not the operating condition of the engine is in the EGR control zone, and a trouble diagnosis condition is satisfied, sensors detect a plurality of engine operation conditions. A trouble diagnosis device receives the output detected by one of the sensors and compares the output with a predetermined value of the same kind as the output a normal state of the EGR system corresponding to the engine condition detected by the sensors, thereby the trouble of the EGR control system is diagnosed. Specifically, one of the sensors detects NOx in exhaust gas or exhaust gas temperature.