Outline Of Diagnosis
WARNING: This page is about a different car, the 2012 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.
Detect malfunctions of the catalyst advanced idling retard angle control.
Judge as NG when ECM is not controlling the angle properly during catalyst advanced idling retard angle control.
Judge as NG when actual retard amount is under the specified value at cold start.