| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to activate a sensor element of an exhaust gas sensor as early as possible while preventing element cracking of the exhaust gas sensor.SOLUTION: A preheating control is executed to control the energization of a heater 16 so as to preheat a sensor element of an exhaust gas sensor 14 in a temperature range that can prevent element cracking due to pouring water on the sensor element until the passage of a predetermined preheating period after starting an engine 11. At a time of this preheating control, first, an energization duty of the heater 16 is set to an energization duty for preheating acceleration to promptly raise a temperature of the sensor element until it is determined that the temperature of the sensor element reaches a predetermined upper limit temperature (for example, an upper limit of an element cracking prevention temperature or a temperature slightly lower than the upper limit). After it is determined that the temperature of the sensor element reaches the upper limit temperature, the energization duty of the heater 16 is set so as to keep the temperature of the sensor element to the upper limit temperature to keep the entire sensor element sufficiently heated state during the preheating control. |
