Abstract: An exemplary embodiment is a system, including an internal combustion engine fluidly coupled to an exhaust gas flowpath, an aftertreatment system disposed in the exhaust gas flowpath, where the aftertreatment system includes a NOx reduction catalyst. The exemplary system includes a processing subsystem having a controller, where the controller includes modules structured to functionally execute operations for determining a catalyst degradation. The modules include a test conditions module, a testing module, a monitoring module, and a catalyst aging module.

Abstract: An exemplary embodiment is a system, including an internal combustion engine fluidly coupled to an exhaust gas flowpath, an aftertreatment system disposed in the exhaust gas flowpath, where the aftertreatment system includes a NOx reduction catalyst. The exemplary system includes a processing subsystem having a controller, where the controller includes modules structured to functionally execute operations for determining a catalyst degradation. The modules include a test conditions module, a testing module, a monitoring module, and a catalyst aging module.

Abstract: One embodiment is a method including providing an aftertreatment catalyst disposed in an exhaust stream of an internal combustion engine and a reductant that reacts with an amount of NOx in the exhaust stream in the presence of the aftertreatment catalyst. The method includes interpreting a catalyst degradation value corresponding to the aftertreatment catalyst, and interpreting a nominal reductant value. The method further includes determining an adjusted reductant value in response to the catalyst degradation value and the nominal reductant value, and injecting the reductant into the exhaust stream at a rate based on the adjusted reductant value.