| 摘要 |
PROBLEM TO BE SOLVED: To make surely diagnosable an electrical error by outputting an error signal even when a sensor signal is temporarily separated from a third range after the change of an electrical heating current is generated within a predetermined maximum time. SOLUTION: The sensor voltage of the sensor apparatus 4 leaves an upper and low limit value range (zone) at a point t1 of time after heating to be in an operable state and a sensor signal is cyclically alternated between a first range of a high signal value and a second range of a low signal value by the control of a controller 2.5. When this signal is present within a third range separating both high and low signals for a period longer than the predetermined max. time, sensor signal line breakdown 1.8 can be certainly detected. However, when the breakdown of a sensor earth line 1.9 is generated, capacity coupling 1.6 is formed by the action of a sensor heater 1.4 to generate a voltage peak. At this time, since sensor voltage is out of the third range, an error can not be detected by known diagnosis. Since the sensor voltage is again present in the zone about 20 ms after the elapse of a voltage peak in this sensor, an error can be detected. |
