The invention relates to a device for the post-treatment of the exhaust gases of a combustion engine (1), characterized in that it comprises, from upstream to downstream: an oxidation catalyst part DOC (3); an outlet (41) of a means (4) for introducing a reducing agent or reducing agent precursor for the selective catalytic reduction SCR of nitrogen oxidesa catalyst part (6) for the selective catalytic reduction SCR of the nitrogen oxides NOx; a particle filter part (7) provided with a catalyst coating for selective catalytic reduction SCRF of nitrogen oxides NOx; and a part (8) for treating ammonia leaks.