Methods for controlling and detecting catalyst poisoning of selective catalytic reduction devices

Method for controlling and detecting ammonium nitrate and/or ammonium nitrite poisoning within selective catalytic reduction (SCR) devices and systems incorporating the same are provided. Methods can include detecting a SCR inlet exhaust gas NO2:NOx ratio above a poisoning NOx flux threshold, detecting a SCR temperature below a poisoning temperature threshold, and determining SCR catalyst poisoning. Methods can further include performing a SCR catalyst cleaning strategy, wherein the SCR cleaning strategy comprises heating the SCR catalyst composition to a temperature above the poisoning temperature threshold. Cleaning strategies can including utilizing a heater, implementing a post-injection, after-injection, and/or auxiliary injection engine strategy wherein the engine is configured to supply exhaust gas to the SCR. Methods can further include arresting reductant dosing, identifying an opportunistic regeneration opportunity, and/or inhibiting performance of an appurtenant oxidation catalyst subsequent to determining SCR catalyst poisoning. The SCR catalyst composition can comprise iron and/or copper.