摘要 |
The method involves sending signals collected by a gas detector (18) arranged in an exhaust gas downstream and with a computing unit (24). The signals are decomposed into a value representative of effective nitrogen oxide amount at a catalyst outlet (16) established by a selective catalytic reduction (SCR) model and a value representative of ammonia amount through an integrated model so as to obtain and evaluate coefficient of disturbance of the detector. Presence of nitrogen compounds downstream from the catalyst is determined when the coefficient is greater than or equal to 1. |