Duramax Fifth Generation: 2011-2016 (LML)
Hello! I am new to this page. A couple weeks ago I had the P20EE code pop up. I added fresh DEF to the tank and cleared the code. About 5 miles later the check engine light came back on followed by the Regen light and three codes on dash, 1) See Owners Manual, 2) Exhaust Fluid Quality Poor, 3)...