| 摘要 |
PROBLEM TO BE SOLVED: To correctly diagnose a dead time delay of a downstream oxygen sensor without depending on the influence of the amount of O2 stored in a catalyst. SOLUTION: This diagnostic device of an exhaust gas sensor for an internal combustion engine includes: an abnormality determination means 12 determining the abnormality of the oxygen sensor 10 downstream of the catalyst based on the output of the oxygen sensor 10 downstream of the catalyst during a period from fuel cut to fuel cut recovery; a predetermined time setting means (step S7) setting a predetermined time from a point of time when fuel cut is started and a point of time when the output value of the oxygen sensor 10 downstream of the catalyst starts movement to a lean state based on the output value of the oxygen sensor 10 downstream of the catalyst when the fuel cut is started; and a time detection means (step S8) detecting an output dead time from the point of time when the fuel cut is started to the point of time when the output value of the oxygen sensor 10 downstream of the catalyst starts to move to the lean state. It is determined that the oxygen sensor 10 downstream of the catalyst is abnormal when the output dead time after fuel cut detected by the time detection means exceeds a predetermined time set by the predetermined time setting means. COPYRIGHT: (C)2010,JPO&INPIT
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