No More Performance: What to Do?

Hi everyone!
My Sharan, manufactured in 2001 with the AUY engine, has no power up to 2000 RPM, which is normal. However, above 2000 RPM, when the turbo should kick in, nothing happens.
The LMM (likely referring to a mass airflow sensor) was replaced 1 month ago, and the timing belt was replaced 1 week ago.
Is the turbocharger broken now???

...unlikely. It's more likely that you have a leak in the charge air cooler system. It might be related to the work that was done on the timing belt. If this problem started happening around the same time as the timing belt service, you should contact the workshop.

What does the error memory say?

AAAAAAAAAAAAAAAAGHHHHHHHHHHH

How are we supposed to know that?

Any statement on this matter is essentially equivalent to saying "then really put your foot down!!!"

This thread is pointless without more information!

m;

After replacing the Z-belt, the machine ran for 3 days.
I checked the error message, and it said something similar to what's described in the 'Hugo001' thread /viewtopic.php?t=9828.17964 - 'Charge pressure control: Regulation limit exceeded.'
P1556 - 35-00 - -
I'm going to check the speaker again today.
Can anyone tell me where the N75 valve, which controls boost pressure, is located?

Can someone tell me where the magnetic valve for boost pressure limitation (N75) is located?

Hm, I would guess that it's located in the engine compartment.

I checked, and I don't see anything .

I checked, but I don't see anything .

Did you hear a clicking sound?

There are no unusual noises to be heard.
What I've noticed is that the thick hose coming from the radiator is sitting relatively loosely on the 'intake manifold.'

There are no unusual noises to be heard.
What I've noticed is that the thick hose coming from the radiator sits relatively loosely on the 'intake manifold'.
And that's exactly where the charge air leaks under load.

That's why this error occurred.

I'm going to my friend's place this afternoon; he has a garage.
Tomorrow, there will be a report.

I detected a memory error.
Exceeded boost pressure limit of 17964.

I checked the thick hose at the connection to the engine, and it's also loose on my friend's.
The funny sensor that is attached to the plastic tube was temporarily replaced for testing.

Is there a way I can check the turbocharger?

Okay, the car is running again. I checked it on the stage, and it turns out the small hose connected to the vacuum sensor on the turbocharger had come off.
Attached, new clamp installed, and the machine is running smoothly again.
Thank you to everyone .