Patent ID: 6831471
Filing Date: 2004-12-14
Classification: F02D

Abstract:
An interface circuit coupled to an electronic control unit and an exhaust gas oxygen sensor, comprising:an amplifier having an input coupled to the oxygen sensor and an output coupled to the electronic control unit; a plurality of different bias circuits for diagnosing the oxygen sensor, said bias circuits being designed in accordance with diagnostic requirements of different types of oxygen sensors; and dynamically configurable means controlled by the electronic control unit for connecting a selected one of said different bias circuits to the amplifier input so that the selected bias circuit is designed in accordance with diagnostic requirements of the oxygen sensor that is coupled to said interface circuit, wherein at least one of said bias circuits receives a reference voltage from said electronic control unit that is adjustable for diagnostic purposes when such bias circuit is selected by said dynamically configurable means, and said electronic control unit includes diagnostic means for setting said reference voltage to a diagnostic value that produces a known output of said amplifier when there is no electrical leakage path between said sensor and another electrical potential, and for diagnosing the existence of an electrical leakage path when the output of said amplifier is different than said known value.