Patent attributes
An ECM determines a failure exist and a failure site in a control valve device from first and second failure diagnoses. In the first failure diagnosis, a failure is determined to have occurred if an opening amount that represents an absolute value of a difference between a detected opening amount and a target opening amount of a valve body is greater than a preset threshold when the target opening amount of the valve body is constant for a predetermined time. In the second failure diagnosis, a failure is determined to have occurred if an opening amount that represents the absolute value of the difference between the opening amount of the valve body when fully open or fully closed and the detected opening amount is greater than the preset threshold when a portion rotating integrally with the valve body has been pressed against a stopper continuously for a predetermined time.
