AUDI: SEE DOCUMENT SEARCH BUTTON FOR OWNER LETTER. THE DIFFERENTIAL PRESSURE SENSOR MAY HAVE CORROSION FORMING, IN SOME VEHICLES, WHICH CAUSES A MALFUNCTION INDICATOR LIGHT (MIL) TO COME ON AND WILL NOT PASS EMISSION INSPECTION OR A POSSIBLE PROBLEM WITH ENGINE CONTROL MODULE (ECM) SOFTWARE. MODEL 2009-2012 Q7. *PE
