Patent ID: 7861515
Filing Date: 2011-01-04
Classification: F01N,F02D,Y02T

Abstract:
1. In an apparatus comprising an internal combustion engine, an exhaust conduit, a particulate filter disposed along the exhaust conduit, an oxygen sensor disposed along the exhaust conduit, and a pressure sensor disposed along the exhaust conduit, a method of diagnosing a performance of an oxygen sensor, comprising: determining a first air/fuel ratio from a signal from an exhaust oxygen sensor; determining a second air/fuel ratio from a temperature upstream of the particulate filter, a pressure differential across the particulate filter and one or more of an airflow into the engine and a fuel flow into the engine; comparing the first air/fuel ratio and the second air/fuel ratio; and diagnosing an error condition of the oxygen sensor if the first air/fuel ratio does not meet a predetermined condition relative to the second air/fuel ratio.