Method and system for using, when confession of the correction to an additive of an exhaust gas stream is seasonable

摘要

The present invention relates to a method for determining when to correct supply of additive to an exhaust gas stream resulting from combustion in at least one combustion chamber (101), wherein the additive is arranged for reduction of at least one substance (NO) resulting from said combustion by supplying the additive to an exhaust gas stream resulting from said combustion. The quantity of additive being supplied is subjectable to correction, and a sensor is subjected to the exhaust gas stream and arranged to measure occurrence of said at least one substance (NO). The method is characterised in:- by means of sensor signals from said sensor, determining a level of occurrence of said first substance (NO) in said exhaust gas stream, and- determining when to correct said supply of additive on the basis of said occurrence of said first substance (NO) in said exhaust gas stream.