Abstract: A method for cleaning an SCR system, wherein reducing agent is supplied to an exhaust flow upstream of an SCR catalyst (260), NOX contents of the exhaust flow are determined upstream and downstream of the SCR catalyst (260) and reducing agent crystals are removed by a high-temperature procedure. The steps are determining (s430) a ratio (K1) between NOX contents downstream and upstream of the SCR catalyst (260), raising the temperature (s440) of the exhaust flow to vaporize reducing agent crystals with a view to cleaning, determining (s450) a ratio (Kn) between respective NOX contents determined downstream and upstream of the SCR catalyst (260) at a temperature (T2) of the SCR catalyst (260) at which reducing agent crystals vaporize, comparing (s460) the ratios (K1, Kn) and using this comparison as a basis for deciding whether reducing agent crystals have been removed to an intended extent.

Abstract: A method pertaining to an SCR system wherein a reducing agent is provided in an exhaust gas stream from an engine (231) for purifying the exhaust gas with respect to among other things content of NOx. The SCR system comprises a vaporization portion (361) being arranged upstream a catalyst arrangement (260; 262) (s410). The method includes continuously monitoring changes of a temperature (Tmod) of the vaporizing portion, controlling (s420, s430) a mode of operation of the engine (231) based on changes of the temperature (Tmod) of the vaporizing portion, so as to operate the engine (231) based on requirements regarding fuel economy as well as exhaust gas purification and at the same time, avoiding formation of crystals in the vaporizing portion (261). Also a computer program product comprising program code (P) for a computer (200; 210) for implementing a method according to the invention. Also an SCR system and a motor vehicle equipped with the SCR system.

Abstract: A method for cleaning an SCR system, wherein reducing agent is supplied to an exhaust flow upstream of an SCR catalyst (260), NOx contents of the exhaust flow are determined upstream and downstream of the SCR catalyst (260) and reducing agent crystals are removed by a high-temperature procedure. The steps are determining (s430) a ratio (K1) between NOx contents downstream and upstream of the SCR catalyst (260), raising the temperature (s440) of the exhaust flow to vaporise reducing agent crystals with a view to cleaning, determining (s450) a ratio (Kn) between respective NOx contents determined downstream and upstream of the SCR catalyst (260) at a temperature (T2) of the SCR catalyst (260) at which reducing agent crystals vaporise, comparing (s460) the ratios (K1, Kn) and using this comparison as a basis for deciding whether reducing agent crystals have been removed to an intended extent.