| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent incorrect judgment and improve diagnostic accuracy. <P>SOLUTION: The device for diagnosing a failure of an oxygen sensor with a heater judges that an oxygen sensor is in a failure state when a negative voltage from the oxygen sensor is detected. In the warm-up process of the oxygen sensor after the start-up of an internal combustion engine, the heater is controlled so that the temperature Ts of a detection element is dropped at least once. By the drop of the element temperature, the outside air can be introduced in an atmosphere chamber by contracting the gas in the chamber. This promotes the exchange of moisture/steam in the atmospheric chamber and the atmosphere and prevents the occurrence of a negative voltage and the incorrect judgment. <P>COPYRIGHT: (C)2009,JPO&INPIT |
