Method for treatment of an exhaust stream, resulting from a combustion in a combustion engine, passing through an exhaust treatment system, and comprising nitrogen oxides NO x, wherein said NO x comprises nitrogen monoxide NO and nitrogen dioxide NO 2; characterised by - an oxidation of compounds comprising one or several of nitrogen, carbon and hydrogen in said exhaust stream, wherein said oxidation is carried out by at least one oxidising component (311, 312 320) arranged in said exhaust treatment system; - a reduction of an amount of nitrogen oxides NO x reaching a reduction catalyst device (331, 332), arranged downstream of said oxidising component (311, 312, 320) in said exhaust treatment system, wherein said reduction is carried out through a catalytic reaction using an additive, and wherein said reduction catalyst device (331, 332) includes a first reduction catalyst device arranged upstream of a particulate filter of said exhaust treatment system to provide a first impact on a first amount of nitrogen oxides reaching said first device and a second reduction catalyst device arranged downstream of said particulate filter to provide a second impact on a second amount of nitrogen oxides reaching said second device; - a determination of a value (NO 2 /NO x) det for a ratio between an amount of nitrogen dioxide NO 2 reaching said reduction catalyst device (331, 332), and said amount of nitrogen oxide NO x reaching said reduction catalyst device (331, 332); and - an active control of at least one parameter related to said combustion engine, based on said determined value (NO 2 /NO x) det for said ratio, wherein said active control is carried out, so that said amount of nitrogen oxide NO x reaching said reduction catalyst device (331, 332) is increased, if said determined value (NO 2 /NO x) det for said ratio exceeds an upper threshold value (NO 2 /NO x) threshold_high; (NO 2 /NO x) det > (NO 2 /NO x) threshold_high. - an oxidation of compounds comprising one or several of nitrogen, carbon and hydrogen in said exhaust stream, wherein said oxidation is carried out by at least one oxidising component (311, 312 320) arranged in said exhaust treatment system; - a reduction of an amount of nitrogen oxides NO x reaching a reduction catalyst device (331, 332), arranged downstream of said oxidising component (311, 312, 320) in said exhaust treatment system, wherein said reduction is carried out through a catalytic reaction using an additive, and wherein said reduction catalyst device (331, 332) includes a first reduction catalyst device arranged upstream of a particulate filter of said exhaust treatment system to provide a first impact on a first amount of nitrogen oxides reaching said first device and a second reduction catalyst device arranged downstream of said particulate filter to provide a second impact on a second amount of nitrogen oxides reaching said second device; - a determination of a value (NO 2 /NO x) det for a ratio between an amount of nitrogen dioxide NO 2 reaching said reduction catalyst device (331, 332), and said amount of nitrogen oxide NO x reaching said reduction catalyst device (331, 332); and - an active control of at least one parameter related to said combustion engine, based on said determined value (NO 2 /NO x) det for said ratio, wherein said active control is carried out, so that said amount of nitrogen oxide NO x reaching said reduction catalyst device (331, 332) is increased, if said determined value (NO 2 /NO x) det for said ratio exceeds an upper threshold value (NO 2 /NO x) threshold_high; (NO 2 /NO x) det > (NO 2 /NO x) threshold_high.