A method for the diagnosis of an exhaust gas purification system for an internal combustion engine

摘要

A method for the diagnosis of an exhaust gas purification system for an internal combustion engine, provided with a pre-catalyst (3) and a main catalyst (5) disposed along an exhaust duct (4) of an internal combustion engine (2); the method including the stages of determining a real heat (QR) supplied to the exhaust gases in the pre-catalyst (3) as a function of a input temperature (TI) and an output temperature (To) of the exhaust gases at the input and output respectively of the pre-catalyst (3) (130); determining a nominal heat (QNOM) supplied during nominal operating conditions of the pre-catalyst (3) (150); calculating an index (I) representative of the state of wear of the pre-catalyst (3), as a function of the real heat (QR) and the nominal heat (QNOM) (160); comparing the index (I) with a threshold value (IS) (170).