Ok 1400 miles on the LBZ, not a code to date and 900+ has been towing, went 350 miles tonight ans had set the code in the first 90 miles, what gives? Fingers got a stick reday yet?

Mine has also done the 401 code twice while towing. I stopped at a dealer and they could not even pull the code, so I went to walmart bought a code reader and saw it was egr and just reset it. It did it again the next day, I reset it and has not happend since.

At some point GM will get sick of people returning to the dealer with meaningless P0401 codes. I'm hoping that their solution will be a flash update as they did with the 05's which was to change the EGR threshold so that exhaust and towing won't trigger the CEL/Code. Time will tell. For now, I am sticking with my egr code eliminator.