why is my valve rattling in my 2013 xc60 t6

 

Geez, that's not a lot to go on so here's some thoughts on self-diagnosis. Does it rattle with the car in neutral at various engine revs. Does it rattle at a specific road speed? Does it change when accellerating? does it change when applying the brakes? Does it change when turning left or right? Where does the sound appear to come from (try sitting in various seats with somebody else driving to get some perspective)? Does it sound tinny metallic or chirpy plastic? If you press on areas of the dash and other trim covers does the sound go away?

With that said, common rattles can be traced to loose trim/covers, engine/exhaust heat shields, brake dust shields (aka backing plates) and junk in the trunk or spare tire well.