Heater control apparatus of air-fuel ratio sensor and method thereof

A heater control method of an air-fuel ratio sensor which is mounted to an exhaust system of an internal combustion engine and equipped with a heater for heating a sensor element, wherein

• an element temperature is detected by measuring an impedance of the sensor element of said air-fuel ratio sensor,
• a power supply amount to said heater is feedback controlled so that the element temperature reaches a set target temperature, and
• at least one of said target temperature of the element temperature and the power supply amount to said heater is restrained to a lower temperature side, compared to other conditions, on a condition that a water content in the exhaust is condensed in an exhaust system.

A heater control method of an air-fuel ratio sensor which is mounted to an exhaust system of an internal combustion engine and equipped with a heater for heating a sensor element, wherein

• an element temperature is detected by measuring an impedance of said sensor element of said air-fuel ratio sensor,
• corresponding to the detected element temperature, an increase component of a power supply amount to said heater is set to be smaller as the element temperature is lower, and the power supply amount to said heater is feedforward controlled to be increased gradually by each increase component from a predetermined initial value.