2017 x15 Coolant system pressure test. Not losing pressure after 20 minutes ??

[ahub86]

Not sure if it fits in with all your symptoms but could the steam/smoke be DEF? I had a DEF doser go bad and drizzle the DEF into the pipe rather than spray. It “steamed” for sure. I just was noticing that your stack looks similar to a DEF stain.

Not pertaining to your situation but a learning story: My doser was drizzling through and I didn’t know it. I was in a job in the morning and left my key on (engine off) listening to the radio while I waited my turn to unload (pressurizing the DEF system, oops). It pumped like 2 gallons into the system. When I fired that up and took off STEAM was an understatement. I learned that the DEF system is pressurized with the key in the run position and if I want to listen to the radio with the truck off now I turn it back to accessory position. Lol