Patent ID: 7036351

Claim:
A method of operating an exhaust gas oxygen sensor for an engine, the oxygen sensor having a electrical heating circuit including a heating element and conductor leads attached to said heating element, where a temperature of the oxygen sensor is inferred from an electrical resistance of said heating element, the method comprising the steps of: electrically activating said heating circuit at an activation value determined in relation to external heat transfer to said oxygen sensor; determining an initial temperature of said heating circuit based on an initial cold start temperature of said engine; measuring an electrical resistance of said heating circuit at said initial temperature; predicting hot operational electrical resistances of said heating element and said heating circuit based on said measured resistance, assumed hot operational temperatures of said heating element and said conductor leads, and a nominal resistance of said conductor leads; and modifying said activation value based on said predicted hot operational electrical resistances, the nominal resistance of said conductor leads, the nominal resistance of said conductor leads, and a nominal resistance of said heater circuit so as to compensate for oxygen sensor variations.