| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a diagnosis unit for detecting a failure state from which a waveform different from that of a detecting signal is outputted when the deterioration and failure of an exhaust gas sensor provided inside an exhaust passage of an internal combustion engine are diagnosed. Ž<P>SOLUTION: The diagnosis unit includes: a detection signal generator 101 for calculating a fuel injection volume containing a detection signal; and an exhaust gas sensor evaluation means for determining a state of the exhaust gas sensor 103. The exhaust gas sensor evaluation means includes: a first band pass filter BF1 for extracting a frequency component of a given frequency band; and one or more other band pass filters BF2 for extracting a frequency component of a frequency band different from that of the first band pass filter. The state of the exhaust gas sensor is determined based on a ratio between the first frequency component extracted by the first band pass filter and that done by the other band pass filter from the output of the exhaust gas sensor relative to the fuel injection quantity. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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