Check engine and low coolant light intermittent

[SAexp]

For the past two weeks my check engine light and low coolant light has been flashing intermittently. I am losing a bit of coolant, about half a gallon ever 600 miles. I had the truck plugged in and the codes checked to no avail. The dpf filter and doser along with the Egr tune up and a new egr valve has all been done in the last year. We replaced the fixed one small leaking hose and replaced the Egr cooler three days ago. Currently the truck is back to doing the same thing. There is not a large amount of coolant in the oil or anything. When the truck was apart the turbo did seem to be tight. Is it possible the coolant is being lost going through the turbo?