Hey Scotty,
I got a 2017 Grand Caravan that's a little over 155k miles that started overheating. Over the last three months I've changed the thermostat, water pump, and installed a new radiator due to a leak (just 3 weeks ago). I've put coolant into it a few times and aren't seeing any leaks from the car. The oil is clean, no white smoke when running it either. Sometimes I also get a P0430 code which says the O2 needs to be checked. I get the feeling this is leading to a head gasket failure. What do you think?
Make sure you've purged any air out of the cooling system. Other than that a head gasket problems sounds likely. You could try one of the head gasket test kits that Scotty has demonstrated. It won't find all head gasket failures, but will find the most common where exhaust gases find their way into the coolant.
https://www.youtube.com/watch?v=v0U8Iyf0kk4
