DEF Header coolant lines reversed and Code 3363

[Auricle]

It happened to me today. After throwing a 3363 DEF code, my Freightliner dealer found that the coolant lines to the DEF unit were hooked up in reverse. Yikes! Fixed quickly and for free, thankfully. I remembered seeing a post or two here earlier but figured it had to be rare. On a side note, if it had been the DEF header heater/control valve, the dealer said they cannot get DEF units at all right now. Cummins is supposedly working on a fix, some sort of virtual "delete" until they can sort it out.

Auricle
2018.5 Seneca TS 12K miles
2015 F-150

[dneeld52]

Let's hope Cummins makes that software delete available. If it's good enough for ambulances and fire trucks, it's good enough for us!