Having some "issues" with my 2018 6.7 with 116k. So about a year and 10k miles ago I took to dealer to do scheduled trans service and a few other minor things. While there they flashed my PCM as there was a recall or TSB on it. After that flash my regens seemed to occur more often but also were shorter. My MPG dropped from about 17.9 to about 16.9 (FYI, I monitor my MPG very closely and those values are over an 8 tank average using actual fuel consumption and not the trucks calculation). I was not particularly concerned. About 2 months ago my CEL came on. I don't remember the code but was something like an air leak or too much air. Kinda thought that was odd for a diesel but whatever. Took it to the dealer. There was a crack in the CAC tube. Also, there was a TSB or recall for another reflash of the PCM. So I get the truck back. After 100 miles or so the CEL comes back on but this time code is EGR valve stuck open. Here is my conundrum; the CEL is intermittent AND mile MPG is now over 19.5 (albeit only 2 tank average). My regens are definitely not as frequent. In fact I think one regen was a forced regen due to mileage and not DPF being full. I have a service scheduled for a week from now but I like the way it is running right now, especially with CEL not on all the time. Need opinions please!

 

The EGR valve isn't hard to replace on these trucks and can be done without removing the whole cooler.

I'd also check and make sure the guts of the cooler (that's what we in the industry call it) aren't plugged up. If they are, then it's time to remove the cooler to swap the guts.

Bottom line: if the valve is stuck open, it'll be breathing its own exhaust more than it should and will plug up your cooler and intake manifolds as well.

I know this first hand because I've cleaned my fair share of upper and lower intake manifolds and valve covers on a 6.7.

 

there are 3 metal gaskets which look similar but are not….difference in passageway holes…line them up as you remove them so you can be certain of reinstall sequence

some of the the valve valve body bolts look identical to the egr tube bolts…..but are made of different materials …if you put the egr valve body bolts in the egr tube position you will never get them out later.


worth mentioning I was on an egr related code gremlin chase and pulled my egr and cooler to inspect them for functionality and clogging…they were fine so I wasted my time .

it was an all day affair for me .