Patent ID: 8171720

Claim:
Method for indicating a non-urea reductant fault in a powertrain comprising an internal combustion engine and an aftertreatment system comprising an aftertreatment device utilizing a catalyst to convert NOx, said method comprising: monitoring a powertrain start-up event; and initiating a non-urea fault diagnostic based upon said powertrain start-up event, comprising: monitoring a NOx content exiting said aftertreatment system subsequent to said powertrain start-up event through a test span, said test span starting based upon said powertrain start-up event; monitoring a measure of NOx content entering said aftertreatment system through said test span; determining a measure of NOx conversion accomplished in said aftertreatment device based upon said NOx content exiting said aftertreatment system and said measure of NOx content entering said aftertreatment system; through said test span, comparing said measure of NOx conversion determined at a start of said test span to said measure of NOx conversion at a later time within said test span; identifying a NOx conversion fall off following said powertrain start-up event between said start of said test span and said later time within said test span based upon said comparing; and indicating a non-urea reductant fault based upon said NOx conversion fall off.