Control system of air-fuel ratio sensor heater temperature for internal combustion engine

A system for controlling a temperature of a heater of an air-fuel ratio sensor installed in an internal combustion engine and generating a signal indicative of an air/fuel ratio in an exhaust gas generated by the engine;

• including;
• the heater installed at the air/fuel ratio sensor and for heating a sensing element of the air/fuel ratio sensor when supplied with current;
• and
• current supply control means for controlling a supply of current to the heater;
• wherein the improvement comprises;
• the engine is a direct injection spark ignition engine which is operated at an ultra-lean burn combustion or at a pre-mixture charged combustion;
• and,
• the system includes:
• sensor temperature determining means for determining the temperature of the air-fuel ratio sensor;
• and
• combustion determining means for determining whether the engine is operated at the ultra-lean burn combustion;
• and the current supply control means controls the supply of current to the heater based at least on the determined temperature of the air-fuel ratio sensor and a result of determination whether the engine is operated at the ultra-lean burn combustion.