| 摘要 |
PROBLEM TO BE SOLVED: To improve diagnosing accuracy while preventing erroneous determination by distinguishing the case of a failure of a sensor from the case of the influence of water. SOLUTION: The failure diagnosis device for the oxygen sensor provided in an exhaust passage for an internal combustion engine determines a failure of the oxygen sensor in accordance with a restored condition when the negative output voltage of the oxygen sensor is restored to be zero or higher. When the negative sensor output voltage is restored to be zero or higher, behavior is different between the case (b) where a failure occurs in the oxygen sensor and the negative voltage is generated, and the case (a) where the oxygen sensor is normal but the negative voltage is generated by the influence of water residing therein. Thus, a difference in the behavior is utilized for distinctly specifying the case of the failure of the sensor or the case of the influence of water. COPYRIGHT: (C)2009,JPO&INPIT
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