NHTSA Complaint #11464256 — 2016 GMC CANYON

We are always getting a code P1478 on our truck when we add def fuel in it when it is time to do so. We have tried to clear it out on our own but never goes away and have to end up taking it to the dealership to get it done. They said it's because the soot it built up. We have always used Blue Def in our vehicles. There was a recall on this system where they have to reset the system or a sensor. I don't understand whey this is always happening, The drivers seat was recalled once for it not being manufactured corrected. It fabic held up a few years when we got the few years when we got the vehicle and it is has done it again. We have asked the dealership about about another recall on the seat and they said they haven't seen one. We have tried to get it fixed on our own but no one have the fabic to do it. It isn't but together very well at all.