Code P0446, EVAP Vent System Performance?

Dear technician,

In my car listed above I very often have the Check Engine Soon notification with this number: No. P0446 and text: EVAP Vent System Performance.
My capable car-technician (experience with USA-cars) told me it has to do with this:
Gasoline vapor in the tank is sucked to the engine through a thin pipe with 2 valves.
Valves are opened/closed by the car-electronics, call it system, and based on that the system says OK (does nothing) or reports the PO 446-error.
Note: he has a device to control & simulate & read the system, below I call it “screen”.

He cleaned and checked the gasoline-inlet if it is closed 100%, it’s OK.
He tested the thin pipe and the valves, no blockage and no leaks.
To be sure he replaced one valve (close to the tank).
To check the wiring, he needs a drawing of the system with the numbers/colors of the wires on it.
Please be so kind to email me that drawing so we can check the wires.
A few more questions:
- Can we test the wires & valves by opening them using the system?
If yes, please send the codes/commands/nrs. We must use on the system’s screen.
- When and based on what sends the system signals to the valves?
- Is there a device that measure a vacuum or something else and sends a signal to the system?
- How to simulate that? Do something with the measuring-device? (If there is one.)
Can we see on the screen of the device-controller what that measuring-device does?
Can we simulate a certain value and hear the valves opening/closing?
- When does the system do what it must do, just by interval or?

In Holland we have a saying:
It takes only 1 fool to drive a 1000 men crazy, just by asking them too many questions.
Now I feel like that fool, hope I didn’t drive you crazy...
Awaiting your answers,
Kind regards,
Adrian B.