Last summer I got the DEF CEL code on my 2013. I went ahead and deleted the DPF exhaust and then tuned to stock with the H&S MIni Max. Did nothing to the EGR. CEL went out and truck has run great for a year. I did not unplug anything on the EGR. I recently saw a video on line about unplugging three wires for the EGR so I went ahead and did that (did this after a year of having them still connected). No noticeable difference. Truck runs the same so I assume the tune just turned off those wires in the first place. However, in order to get to the third wire clip that is located just behind radiator under the cold in tube, I removed that wire clip that holds on the black plastic tube and pulled the tube off. I noticed that inside the aluminum housing where that black tube attaches was full of what looked like black slime and gunk. It almost looked like thick grease but super black. I cleaned it out as best I could.

Is this black slime because the EGR is "Tuned off" and I do not have block off plates or anything? Can I just leave it like it is? I do not care if the EGR goes bad because I am in Texas and we do not have emissions tests. Or, is there a reason I should go ahead and put the block off plates on? If I do not need to, I would prefer to just leave it unless it will cause a problem down the line (Again, it has been this way now for a year and about 20k miles.) Truck has 109000 miles.