To provide an exhaust gas sensor furnished with a sensor element confronting inside the exhaust pipe of an internal combustion engine, a sensor heater for heating the sensor element, and a cylindrical protector covering the sensor element and having a plurality of vents, wherein the sensor element is prevented from cracking caused by water covering (condensate from the exhaust gas).
The protector 4 is formed in a double structure with an outer cylinder 5 and inner cylinder 6, wherein a vent 5a in the outer cylinder 5 is dislocated from a vent 6a in the inner cylinder 6. A protector heater 8 for heating the protector 4 is installed in the position on the inner cylinder 6 mating with the vent 5a in the outer cylinder 5. To the protector heater 8, current is fed at the same time as the start of the engine, and the current feed is ended when the exhaust pipe wall temperature reaches a temperature causing no condensate.
HOSHINO KAZUHITO
UNIKI KAZUMASA
NISSAN MOTOR