Patent ID: 8863499

Claim:
An exhaust gas treatment system for an internal combustion engine, comprising: an exhaust gas conduit in fluid communication with, and configured to receive an exhaust gas from the internal combustion engine; a diesel exhaust fluid (“DEF”) source in fluid communication with the exhaust gas conduit, the DEF source supplying a DEF having a quality factor; a selective catalytic reduction (“SCR”) device in fluid communication with the exhaust gas conduit and configured to receive the exhaust gas; a NO x sensor in fluid communication with the exhaust gas conduit, the NO x sensor located downstream of the SCR device and configured for detecting a NO x concentration value; and a control module in communication with the DEF source and the NO x sensor, the control module comprising a set of electronic circuits configured to: store a diagnostic adaptation factor and an expected NO x value, wherein the diagnostic adaptation factor is an indication of the quality factor for the DEF; determine a controls adaptation factor based on a deviation between the NO x concentration value and the expected NO x value; selectively update the diagnostic adaptation factor with the controls adaptation factor; preserve the selectively updated diagnostic adaptation factor if a reductant fluid quality test is determined to be failed; and reset the selectively updated diagnostic adaptation factor to a nominal value if the reductant fluid quality test is determined to be passed.