10-4 Challenger. Back a month or so ago, I replaced that Diff sensor. One of the first suspects. Ive pulled those hoses, AND disconnected from the plugs, and blown air thru them. It passes thru no problem, but I always wonder if theres a little rock, or piece of debris in there that lets the air go thru, but still throw the pressure enough to kick it into regen. I have heard it happens at VERY little pressure difference. Im putting things back together today, My egr cooler was taken down to a local shop to be cleaned, and they just called and said its ready. I just dont have the space or tools to do it myself. I have a brand new pipe going on behind the injector, new exhaust gaskets all the way back to the DPF, 7th injector cleaned again, and new gasket/seal. Nothing really stood out, other than that pipe being completely destroyed. I cant believe transport Equip in Missoula replaced my flex pipe, directly behind this one, and never noticed it was rotted through, but hey, It was wrapped in heat tape. One other glaringly odd thing I found,....... Mack Techs encouraged to chime in, PLEASE. Below My DPF filter, in the bottom piece of that assembly, There is a hole. If you drop the WHOLE DPF, top piece, catalyst, filter, and bottom piece, and set it on the ground there is a plate/bracket welded to the bottom, that keeps it from just wobbling over on its side. Well, when we got it off, I noticed soot coming out of under that plate. And after looking inside, there IS a hole going thru it. I believe, it may have had a plug? or been epoxied over? Kinda like a relief valve in case Backpressure gets to high? Am I way off base, or did someone just drill a hole in the thing somewhere down the road? TEC has had this thing in, and all taken apart, when they cleaned my filter, and they never said anything about it, But it does seem like I saw it once, and it had some kinda brownish gunk in it. I dont know, maybe its supposed to be there, to drain liquid, but it HAS to affect the pressure in the bottom half of the assembly. Fingers crossed,.. Ill be firing it up in a few hours.