CBBB Error Code: Troubleshooting & Solutions

Hello fellow diesel mechanics,
I need your help again. Today, while accelerating gently after about 20 minutes of driving, the engine went into limp mode, with the glow plug indicator flashing. Shortly after, on the company parking lot, the engine turned off and then restarted, and the warning light went out. Then, on the way home, after about 20 minutes, the engine felt like it had no power, and shortly after that, it went into limp mode again while going uphill. The read-out values are shown below. I've visually inspected the engine as much as I can see, and everything looks fine. When the engine is cold, it seems like the power is fully there. There's no smoke before, during, or after the limp mode. What else can I check myself?
Mileage: 133,000 km.

Address 01: Engine Control Module (ECM)
Label file: DRV\03L-906-022-CBA.clb
Part number SW: 03L 906 022 RB, HW: 03L 906 022 BQ.
Component: R4 2.0L EDC G000SG 3615
Revision: 13H01--- Serial Number: AUX7Z0I8FNF0Q1
Encoding: 0000172
Operating number: WSC 18432 679 542760.
VCID: 76E42B81011426F1C9-8023

"One error found:"
000665 - Charge pressure control.
P0299 - 000 - Regulation limit exceeded.
Environmental conditions:
Error status: 01100000
Error priority: 2
Error frequency: 1
Lost Count: 255
Mileage: 133,820 km
Time: 0.
Date: 2017.04.10
Time: 06:22:32

Environmental conditions:
Speed: 2553 RPM
Speed: 125.0 km/h
Last: 100.0%
Pressure: 2499.0 mbar.
Pressure: 1989.0 mbar.
Lambda: 84.4%
Lambda: 35.5%

Readiness: 0 0 0 0 0

Hi,

check:
- Leak in the charge air cooler system.
- Vacuum system for controlling the loader.

Best regards, Rainer.

small update;
Even with a cold engine, a noticeable loss of power is felt across the entire RPM range. Today, after 30 minutes of driving, the error (limp mode) could not be triggered.

As far as I could tell, I checked the air ducts and didn't find any leaks, chafing, or similar issues. The vacuum system also appears to be sealed properly.

I have run the "Block 011: Test of Turbocharger Pressure Control (LDR)" multiple times with a cold engine. The result showed a difference of approximately 240 mbar from idle speed to test speed. Then, after 30 km with a warm engine, I ran the test again, and there was no change in turbocharger pressure from idle to test speed. Unfortunately, I don't have a vacuum pump with a pressure gauge in stock, so I can only use my mouth to create a vacuum on the pressure sensor. I can see that the threaded rod is moving, but I can't really "hold" it. How should the vacuum behave at the sensor? I should at least feel a slight "sticking" of the hose to the diaphragm, right?

The vacuum chamber on the turbocharger must be airtight.

Okay, I just checked it again using a vacuum pump, and it's still not able to create a vacuum.
I'm assuming the vacuum sensor is defective. Can the vacuum sensor be removed from my engine? I see three screws on the housing on the right side, which shouldn't be a problem. However, the threaded rod for the adjustment is located between the turbocharger and the engine block. Can I determine the correct setting later using VCDS? By the way, is the sensor even available as a replacement part?
Greetings.

The pressure sensor has been replaced, and the boost pressure is back. Attached are two photos: one showing the disassembled sensor and its components, and the other showing the actual problem – a crack in the lower membrane.
Best regards,