My Moho is on a Ducato Euro 6 150 go. base. It’s only 6 months old with 4000 miles. The engine has developed a high pitched whistling noise which changes pitch with engine noise. I am in Spain at present so a little concerned about taking it to a dealer. There is no discernible fall off in performance. Someone on another forum has suggested it could be the idler bearing on the auxiliary belt tensioner. Is this a serious problem? Any advice would be most welcome.