I have looked everywhere and read all the fault code list for the DEF system and I never find my code! Getting irritated I keep getting EEC61 SPN004336 def air valve 05. It comes and goes as I pleases. Just starting to get annoying anyone ever have this code? (2013 Freightliner Cascadia) what is the cause for this annoyance? Thank you in advance, and as always be safe out there.