Carbon Monoxide/Fumes inside cab of a 2016 PETERBILT 587 Please HELP

This truck was a 2016 new purchase in October 2017. On lot new from the dealership. Have had it in the dealership 4xs for a total of 26 days. There have been multiple issues. Some fixed others not. Most pressing issue though is CO coming into the cab. The dealership claims there's nothing there, yet driver experiences multiple CO poisoning symptoms. (headaches, dizziness, nausea, sleepiness, confusion, back pain, chest pains, and hallucinations.) We've purchased meters and air quality indicators. Those from home weren't any good. The latest is a model that reads from zero ppm and up.
This past weekend it alerted at 9ppm and then again today at 12ppm. If we take it back again, which we will have to, how can we get them to actually fix it? Should we get a diagnostic somewhere else first?
There's a white smoke that he sees. No noises. No pulling on the engine, or loss of power.
Gotta be either DEF or EGR issues.

We have looked for attorneys to assist but as of yet not found anyone willing to help.

The truck was manufactured April 2015 it has a Cummings ISX engine.

Does anyone know of any other common issues with this truck or have any suggestions to get it fixed? ASAP this truck is not safe for him. He has to ride with windows down at all times and a fan blowing to keep the air safe. Whenever it rains and he has to close windows or turn on the defrost/heater/AC he gets sick.

 

It's our own / only truck. My husband IS the driver. Nope, don't wanna get rid of him. And its by no means "a little fumes" He's driven 17years. he's ok with "normal" fumes. CO is deadly

 

PLease tell me how the shop can find IT. What tests need to be run. As I've said, we HAVE taken in to the dealership 4 FOUR times. They say there can not fimdany exhaust/fumes.
We know this is dangerous. Thank you for understanding

 

Thats a good idea. We'll try to get that and see how that works out. We've made a few videos of the "soot" on certain parts of the motor. So, those could be areas that we could place the CO meter.