What would cause my DEF mileage to start dropping? Could a bad one box be doing it? I have a 2013 Cascadia with a 2012 dd15 in it. ANY help would be appreciated!
Sorry your going through that .My 2012 caused me so many problems but usually when my DEF mileage dropped it was a knox sensor getting ready to go ,good luck i finally did a delete after replacing the knox sensors more times than I can remember and everything else from harnesses to the one box and continued to have problems until the delete been 3 yrs and no problems