N75 Valve Not Activating on VW Passat 2.0 TDI

Hello everyone.

I'm having the following problem.
Vehicle: VW Passat 3C, 2.0 TDI engine, engine code CFFB.
After the vehicle has been running for a few minutes, the heating element suddenly starts to blink.
Error code P256300.
I checked the pressure in the container using a vacuum test, and it was within the acceptable range.
The charger was replaced despite being in good condition, due to its high mileage.
The problem still persists.
The vacuum at the solenoid valve is only 0.2 bar when idling. At the N75 valve, it's 0.7 bar. The N75 valve is receiving 12V.
When it's activated, it's fully engaged (or at 100% power), and the valve opens completely. After a few minutes, the engagement is completely disengaged.
Leitungen vom N75 zum Steuergerät durchgemessen. Are you okay?
The water tank is quite damp. My guess is that the control unit is malfunctioning.
My question is, is the main input for the boost pressure control the mass airflow sensor? Should I replace it again? It's possible that it's sending a false value to the control unit, which is causing the N75 valve to be deactivated. Thank you in advance.

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