| 摘要 |
PURPOSE:To prevent the occurrence of cracks on an element by a thermal shock caused by the moisture contained in the exhaust gas and stuck on the element of an oxygen sensor. CONSTITUTION:An oxygen sensor 6 stores a heater 10, and a sensor element is activated by the heating of the heater 10 when the exhaust temperature is low. It is detected that the ignition switch 15 of an engine is switched from on to off, and the heater 10 of the oxygen sensor 6 is forcefully excited for a preset period after the switch 15 is turned off. The temperature reduction of the sensor element due to the operation stop is suppressed by the heating of the heater 10, and the moisture contained in the exhaust gas is prevented from being stuck on the sensor element. |
