2008 Maxxforce DT. Emissions light is illuminated on the dash (exhaust blowing through exclamation point). Using ServiceMaxx I pull code 2175 VGT performance fault, In the IKNOW section it has you check the VGT actuator harness for any shorts or break in the harness. I traced the harness and it looks ok. The VGT acuator moves free, I called International about the code and they said for me to replace the turbo as the VGT actuator is not servicable. So before I spend $2200 on a new turbo, I swapped a turbo from another bus to see if it would fix the code and wouldn't you know it, the code remains. The bus with the supposedly bad turbo runs just fine with no codes. The bus with the active code runs just fine also. My brain hurts I'm hoping someone can help me out.
I have had several of these engines with this dtc only **and sometimes comes in with the egr fault as well , what we have found on several of them is the pwr relay (schematic says pwr relay **but in rear fuse box its the Turbo relay faulty at times and check the pins for corrosion may be intermittent or inop totally . This dtc is basically a can H communication fault or faulty vgt .
Had same issue on a couple of my 2009 bus's. Each time it was the actuator, all tests came out good, found i could get actuator from turbo rebuilder shop.
Diagnosing a 2014 ISL now. Intermittent VGT codes. Passes testing with Insite but Im not convinced. Instead of a clean and crisp "zip zip zip" sound when you turn the ignition on it sounds like someone eating a bowl of capn crunch. Its gonna seize up sooner or later. Just another thing to listen for when working on these buses with VGTs.