I'm in aftertreatment homeschool

[Punchy]

I've been running this truck for just about two years. It was used to deliver dry and reefer groceries from manufacture up until 2020 as far as I know. I'll dig into whatever fleet mechanic notes I can find from them.

I have a list of the codes I've seen since May when the truck began running differently, when I started scanning. Worse fuel consumption, a "hitching" at times during acceleration, rougher idling. I do remember seeing the 102/16 and 102/18, alongside the 1569/31. Those three alternate in and out in recent weeks. I got rid of those 102s before by doing my PM earlier than usual: Oil and filter, fuel filter and fuel-water separator. But they've returned in the last two months, as the aftertreatment system has developed more issues. Those three are the usual suspects I've seen. I'll list the others that came and went, when I get back to my notebook.

I haven't seen it lose coolant. I drained and replaced that when the topside/turbo DPF doser was switched, and the level still seems okay. Oil consumption starts at around 10K after oil change. Then it's downhill and I'm adding a quart maybe per 1,000 miles after that. I was changing oil at 15,000 to 18,000 when I got the first truck (also Cummins). I do it around 12,000 now.

EGR-related tune-up? None by me, and no mechanic has ever suggested performing that procedure to me in the five or so years I've had my own trucks and started learning to maintain and repair them. I've done things like air bags, replacing fittings elsewhere on the air system/tanks. Oil and filter and fuel filter changes, keeping tires inflated with a gladhand-fitted air hose. Minor electrical stuff like fuses and headlight wiring. Replacing the starter, air dryer cartridge, AD-IS unit, crankcase filter and sensor, crankshaft sensor, IMAP sensor. Other what I consider, basic things that most anyone could do.

Everything I know mechanically is related to issues our trucks have, that I then researched best I could while gathering tools for such issues, and finally I did what I needed to do to keep it going. It's worked out almost every time although I need a lot longer than a shop or a knowledgeable wrench-turner would take... but yeah, kinda slapdash. Wish I'd come across your forum a few years ago.

The only EGR item I swapped on this truck is the sensor there. Your playlist videos alerted me to the actual components such as EGR valve and cooler. I'm on the case to remove, inspect and clean. Other drivers with their own trucks don't know and don't care to discuss this stuff with me; they just pass their trucks to the shops. I have a precious few in my contact list that do know and will talk, but these usually have DD or CAT and can mostly give me principles, not real info on a Cummins. Of course the mechanics (again with a few exceptions) act as if I'm bothering them, or taking money out of their pocket, when I approach with my many questions.

I will check for the DEF doser you say is deeper in the system. The DPF doser which I've apparently mislabeled, and was changed this month, even the parts guys and dealership don't call it the right name. How do I know as much as most of them do, and I just started touching this stuff some weeks ago? As far as I know, the DPF doser has never been changed until I saw someone on YouTube discuss it, which motivated me to open all that stuff up and change it myself. I asked a few shop managers about the symptoms and codes, and every time I got "New turbo" and/or "Take the entire system apart and bake before anything." Is that correct? We're stepping up to that second one shortly (will definitely show pictures) but the first suggestion seems kneejerk and predatory. Again, never heard EGR mentioned and I reach out to a lot of people, sometimes out of my time zone in shops and dealers I'll phone randomly just to pick some stranger's brain.

The photos here are of the old snapped-off temp probe I removed, "temp 3", and of the flexible metal coolant hose to the DPF doser, inlet I'm guessing, next to the new hose. I had no idea what I was looking at, at first, didn't know that those two nuts are separate components because everything was so seized up. You see I chewed the hose nut up with a pipe wrench and still could barely get a twist. I drained the coolant, detached the other end of that hose from the block, and then twisted loose the entire old hose, then unscrewed the entire doser (after unplugging and after unscrewing the fuel hose). Because the outlet coolant hose there, its two nuts are seized as well. Yes, it's been fun.

I'll bring someone in with proper software to plug in ASAP.