A method and system for monitoring an exhaust gas sensor

摘要

A method and system for monitoring a post-catalyst exhaust gas sensor (64,66) in an engine (12) is provided. The engine (12) includes a cylinder bank (16) coupled to a catalyst (52) and an exhaust gas sensor (64) disposed downstream of the catalyst (52) generating a first signal. The method includes supplying a rich air-fuel mixture to the cylinder bank (16), supplying a lean air-fuel mixture to the cylinder bank (16) to supply oxygen to the catalyst (52) and includes indicating the exhaust gas sensor (64) is degraded when the first signal does not indicate a lean air-fuel ratio after supplying the lean air-fuel mixture for a first predetermined time period.