A6 Goes into Safe Mode: Troubleshooting Guide

Hi,

A 2001 A6 V6 TDI with an AKE engine sometimes goes into limp mode for no apparent reason.

When accelerating fully, the engine control unit (ECU) demands 2300 mbar, but the turbocharger actually produces 2560 mbar.
And sometimes, you're driving with a lot of throttle, you briefly lift off the gas, and then the boost pressure drops, and the speed continues to decrease (it should be 2000 mbar, but it slowly drops from 1800 mbar down to 1100 mbar).

What would you guess? The car has already had its 3rd turbo installed, the last one being half a year ago... is it broken again?

Of course, the obligatory error message 'Charging pressure exceeds limit' is also missing.

Interestingly, he sometimes does it very frequently, while other times he doesn't do it for hours.

Is N75 okay?
Is G71 okay?
Is G70 okay?

CU Gremlin.

N75 is okay... (the basic on/off setting works, and the lever adjustment functions).
The LMM has also been newly received.
and the intake manifold pressure sensor is also okay according to the readings.

Throwing away the N75 valve... how can you be sure that the valve won't occasionally get stuck?

Best regards, Rainer.