| 摘要 |
PROBLEM TO BE SOLVED: To improve both diagnostic accuracy and diagnostic frequency. SOLUTION: This diagnostic device for an EGR device is provided with a device 41 capable of controlling the opening of a throttle valve regardless of an accelerator pedal. When diagnosis authorization conditions are materialized, a constant holding means 45 holds the opening of the throttle valve constant, and in the constant opening held state of the throttle valve, an EGR valve adjusting means 46 changes the opening of an EGR valve by a predetermined opening degree. A measuring means 47 measures the change of intake pipe pressure caused by the opening change of the EGR valve, and on the basis of the change of intake pipe pressure, a judging means 48 judges whether there is a failure in the EGR valve or an EGR valve control device 41.
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