Honda Giken Kogyo Kabushiki Kaisha

Akihiro Shinjyo

Hiroshi Kitagawa

Toshihiro Mibe

An apparatus for accurately and promptly determining a failure of an oxygen concentration sensor. The oxygen concentration sensor is arranged at a location downstream of a catalyst in an exhaust system of an internal combustion engine. The apparatus measures a time period elapsed after termination of a fuel cut-off operation, and calculates an integrated amount SUMSVS of exhaust gases exhausted after the termination of the fuel cut-off operation. A failure of the oxygen concentration sensor is determined depending on whether or not a signal value SVO2 of a signal from the oxygen concentration sensor has crossed a predetermined threshold value &num;SVO2CHK. Further, when a predetermined time period &num;TMFCCKD has elapsed, if the signal value SVO2 has not crossed the predetermined threshold value &num;SVO2CHK, and at the same time when the integrated amount SUMSVS of the exhaust gases has not reached a predetermined value &num;SUMSVAFC the failure determination is suspended.

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Saitama-ken, Japan

Akihiro Shinjyo