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 for troubleshooting in an SCR system which has a dosing unit (250) for dosing of reducing agent into an engine's exhaust duct (290) upstream of an SCR catalytic converter (270) for reduction of NOx content in an exhaust flow from said engine and a DOC unit (259). The method comprises steps of: determining (s310) NOx content in the exhaust flow downstream of said SCR catalytic converter (270); determining satisfactory operation of said SCR catalytic converter (270); progressively altering the dosage of said reducing agent; determining whether said SCR system can reduce NOx content of the exhaust flow downstream of said SCR catalytic converter to a predetermined extent during altered dosing; using the results of determinations as a basis for deciding whether said DOC unit (259) is faulty or not. Also disclosed is a computer program product having the program code (P) for a computer (200; 210) for implementing the method according to the invention.

Abstract: A method for troubleshooting in an SCR system which has a dosing unit (250) for dosing of reducing agent into an engine's exhaust duct (290) upstream of an SCR catalytic converter (270) for reduction of NOx content in an exhaust flow from said engine and a DOC unit (259). The method comprises steps of: determining (s310) NOx content in the exhaust flow downstream of said SCR catalytic converter (270); determining satisfactory operation of said SCR catalytic converter (270); progressively altering the dosage of said reducing agent; determining whether said SCR system can reduce NOx content of the exhaust flow downstream of said SCR catalytic converter to a predetermined extent during altered dosing; using the results of determinations as a basis for deciding whether said DOC unit (259) is faulty or not. Also disclosed is a computer programme product having the programme code (P) for a computer (200; 210) for implementing the method according to the invention.

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.