AGR valve open or closed without vacuum hose?

Hello everyone,
I have a question about the AGR valve.
Vehicle: VW Passat 3B6, year 2004, 2.5 TDI engine (engine code BDH, Euro 4 standard), 132 kW, mileage 400,000 km.

Since the EGR valve is controlled by vacuum, I always assumed that the more vacuum applied, the more it would open.
Unfortunately, that is not the case.
When the engine is idling (at operating temperature, with the vacuum hose disconnected), VCDS displays an actual value of over 400, even though the target value is only 208.
When I connect the hose, the value changes downwards, also to 208.
If I disconnect the hose and connect a manual vacuum pump, I can bring the value down to 115.
Therefore, the valve closes further the more negative pressure is applied.
Apparently, it should close completely at engine speeds above 2500-3000 RPM.
I haven't tested whether that is the case yet. Coming soon.
My question regarding this is:
Who among you can tell me more about that?
Is it the factory setting that the AGR valves are fully open without vacuum?
Is mine possibly broken?
I replaced it at 330,000 kilometers.

"I would appreciate any information on this."
Thank you for reading.

HG
Michi.

You're just thinking incorrectly.

Air mass exceeding 400mg/stroke in the lower limit = no EGR.

The engine requires approximately 450mg of air mass per stroke at low load. So, if you have an "as-is" value of 200mg/stroke, the remaining 250mg/stroke comes from the EGR, and therefore is "not visible" to the mass airflow sensor (MAF).
However, if the 450mg per injection passes through the LMM (likely referring to a mass flow meter), then nothing will come from the EGR (likely referring to an exhaust gas recirculation system).

The ARG valve functions as expected:
No vacuum = valve closed.
max. Vacuum = Vent fully open.

@ Michael
"I'm completely confused right now, Michael."
The actual value of 400 that I specified refers to 400 mg/hour of exhaust gas recirculation (EGR) flow rate.
Since you're now talking about air masses, I'm no longer sure if we're addressing the same problem.
If the vacuum hose is disconnected and VCDS shows an exhaust gas recirculation (EGR) flow rate of over 400mg/H, then the EGR valve cannot be closed.
When I connect the hose, the value changes to a lower reading, approximately 208 mg/H for exhaust gas recirculation. Relatively consistent with the target value for the amount of EGR (Exhaust Gas Recirculation).

Am I still wrong???

The value represents the air mass currently being measured by the mass airflow sensor (MAF).

The AGR (Abgas Rückführung - exhaust gas recirculation) system attempts to reach the target value by mixing exhaust gases, which reduces the amount of air flowing through the mass airflow sensor (MAF). You never directly see the returned amount, but only the fresh air flowing over the mass airflow sensor (MAF), and if that's correct, then the exhaust gas recirculation (EGR) rate is also correct.