| 摘要 |
PROBLEM TO BE SOLVED: To prevent the element cracking of an air/fuel ratio sensor caused by the scattering of the moisture bonded to the wall surface of an exhaust pipe. SOLUTION: An oxygen concn. detector is equipped with the air/fuel ratio sensor 1 provided to the exhaust pipe of an engine, a heater 4 for heating the air/fuel ratio sensor 1, heater current supply means 6, 10 for supplying a current to the heater to heat the air/fuel ratio sensor 1 to activating temp., a judge means 100 for judging whether moisture is bonded to the wall surface of the exhaust pipe, and a curren supply restricting means 100 for restricting the supply of a current to the heater 4 by the heater current supply means when the bonding of moisture to the wall surface of the exhaust pipe is judged by the judge means. A flow velocity suppressing means 100 for suppressing the flow velocity of the exhaust gas of the exhaust pipe of the engine when the bonding of moisture to the wall surface of the exhaust gas is judged by the judge means is provided, and the judge means judges whether moisture is bonded to the wall surface of the exhaust pipe on the basis of the temp. of the exhaust pipe. |
