Patent ID: 8201444

Claim:
Method for indicating a malfunctioning catalyst in a powertrain including an internal combustion engine and an aftertreatment system having an aftertreatment device utilizing a catalyst to convert NOx, the method comprising: monitoring an actual NOx content exiting the aftertreatment system; monitoring factors affecting conversion efficiency of the aftertreatment device; determining a predicted threshold NOx content exiting the aftertreatment system for an exemplary malfunctioning catalyst based upon the factors affecting conversion efficiency; comparing the actual NOx content exiting the aftertreatment system to the predicted threshold NOx content exiting the aftertreatment system; and indicating a malfunctioning catalyst based upon the comparing; wherein monitoring the factors affecting conversion efficiency comprises: monitoring a NOx content entering the aftertreatment system; monitoring a bed temperature within the aftertreatment device; monitoring a space velocity within the aftertreatment device; and monitoring an amount of ammonia storage within the aftertreatment device.