Stop engine light and oil coming out of blow by hose.

How much oil is coming from the blowby tube? Is the oil level over full? The warning lights are because your aftertreatment is reaching level 4 warning and/or an improper regen is being detected. If you are getting any face plugging or catalysts codes it is because the aftertreatment is not getting to temp. There are several reasons for this, but the most common are simply dirty components. You mentioned the DPF was recently cleaned, did you also remove and clean the DOC? How about the after treatment injector? That also needs periodic cleaning or replacement. The after treatment system will become prematurely clogged if your engine is burning excessive oil. This issue needs to be looked at too.

 

Ok, well obviously you have a major issue with oil coming out like that. Make sure the oil drain in the crankcase filter housing is not obstructed. If ok there, I suggest a proper blowby test. There is a specific Cummins adapter fitting for this. The turbo or air compressor could also be pressurizing the crankcase and causing excessive oil to be burnt and further plugging the DOC.

 

If it didn’t just all the sudden start running rough, loose horsepower, and start spitting oil out the vent tube then I would be looking more into the emissions components. Otherwise, going the other direction I would want to check the compression and go from there.
If its running warmer that also points more to maybe something plugged in the exhaust system which would likely also force exhaust into the crankcase, but I didnt notice you saying anything about loss of power unless I misread.

ETA: do you still have decent oil pressure?

 

The Dozer injector I think is recommended to be replaced every 250 to 300k if not at least cleaned, It will cause ALOT of problems in the aftertreatment system if its dirty. Also if your throwing that warning light alot after idling then the DPF filter needs to be looked at, Cummins changed the design of them here recently if you dont have the updated model you will have issues. I changed DoC, DPF and Dozer 120k ago and have not had a issue with the aftertreatment system sense.

 

My advice to you is to get rid of that EGR truck! All you are going to do is pay more in fuel and truck parts and labor! All that heat is burning out those parts and that engine wont pass a million miles. Yesterday in Okechobbee fl saw a 2014 ambulance being towed and its the EGR!. Right now you should've been trucking and you are doing what that engine originally was designed to do! make more money for the dealers! The heating is the first sign that engine is going out! They don't pass 800,000mi.