FIELD: machine building.
SUBSTANCE: invention refers to operating and diagnostic method of neutralisation system of waste gases with selective catalytic reduction (SCR). There recorded is signal (S) of waste gas sensor (25) located in the flow direction after catalyst (5) of SCR and having sensitivity to nitrogen and ammonia oxides, in normal operating mode, in compliance with the model of filling level with ammonia accumulated in catalyst (5) of SCR, to catalyst (5) of SCR there supplied is ammonia so that ammonia filling level (F) of catalyst (5) of SCR is maintained approximately at the specified nominal value or in the specified range of nominal values. Normal operating mode is interrupted if there recorded is signal of waste gas sensor (25), which exceeds the specified first limit value (G1), and specified dosing speed of carbamide is increased by the specified value in comparison to the value provided in normal operating mode. Then, depending on characteristic of signal (S) of waste gas sensor (25), the return to normal operating mode or switching to mode of diagnostic operation is performed.
EFFECT: providing improved detection of failures and reliable operation.
