| 摘要 |
PROBLEM TO BE SOLVED: To effectively improve the accuracy of failure diagnosis with respect to an exhaust device of an engine by performing failure diagnosis of an EGR device and failure diagnosis of oxygen sensors at appropriate times when they do not affect each other. SOLUTION: When fuel is cut in deceleration, an oxygen sensor diagnosing process (S7) is performed for diagnosing failure of the oxygen sensors 20, 22 based on change of their detection values, an EGR valve 26 is opened or closed and an EGR device diagnosing process (S11) is performed for diagnosing failure of the EGR device 24 based on change of intake pressure at that time. The performing times of the two diagnosing processes are set so that an opening degree of the EGR valve 26 in the EGR device diagnosing process (S11) does not change in a period (t1-t4) of diagnosis during the oxygen sensor diagnosing process (S7). COPYRIGHT: (C)2010,JPO&INPIT
|
