Thank you the clarification, I was a Ford tech and all manufacturers do it a little differently. I wanted to give him some information as I didn’t have time to study the manual. Do you know if they are monitoring the tank temperature and how are they changing that to run the evap monitor or is it continuously monitored.
I don't know the testing protocol parameters. I suspect it is like most in that the fuel level is neither full nor empty before it checks. They don't monitor tank temp that I'm aware of, just using the difference in pressure/vacuum cause by changes in temp to check for a leak.
We did discuss the system and the charcoal canister vents to atmosphere at times. That should prevent pressure build up in the tank. Best we can come up with is a plugged hose, fitting, or pinched line. Maybe the large fitting on top of the tank at the right side, and or the discriminator valve is malfunctioning. It is also possible that the NVLD is plugged but that typically throws a code.