Current control method for an oxygen sensor heater

A method of operation for an exhaust gas oxygen sensor of a motor vehicle engine, the sensor having an integral heater element that is supplied with electric current to heat the sensor to a desired operating temperature, the method comprising the steps of:

• estimating a temperature of the heater element based on an electrical resistance parameter for said heater element;
• establishing a target temperature of said heater element for heating said oxygen sensor to said desired operating temperature;
• supplying electric current to said heater element based on a deviation of said estimated temperature from said target temperature so as to drive said estimated temperature into correspondence with said target temperature;
• and
• adaptively updating said electrical resistance parameter to compensate said estimated temperature for deviation of an actual electrical resistance of said heater element from an expected electrical resistance of said heater element.