Inspect Doser Valve

Remove Doser Valve cover (4 bolts, 15 mm) remove doser valve using allen wrench Turn truck on normal conditions, Doser valve will spray DEF into mist unplug DEF line, If DEF is pressurized and present, doser valve is clogged or has electrical issues. DEF doser valve is a final check on the operation of DEF system, if doser is spraying def that’s a good sign. Suggestion: take a look through the def hole into dpf housing, if large accumulation of def is present clean it up.