| 摘要 |
PURPOSE: To provide a heater controller for air-fuel ratio sensor which can prevent the deterioration of a heater and sensor element caused by heating by activating the sensor element in an early stage at the time of starting the sensor element. CONSTITUTION: A heater controller for air-fuel ratio sensor is constituted of a power supplying means A which supplies electric power to a heater 17 for heating an air-fuel ratio sensor 15 provided in the exhaust system of an internal combustion engine so as to maintain the sensor 15 in an activating state, resistance value detecting means B which detects the resistance value of the heater 17, and power control means C which controls the electric power supplied to the heater 17 so that the resistance value of the heater 17 detected by the detecting means B can become lower than a first guard value for preventing the deterioration of the heater 17 during the warming-up period of the sensor 15 and lower than a second guard value which is lower than the first guard value after the sensor 15 is warmed up. |
