DSG Failure: 2.0L BKD Engine Stalls While Reversing

Vehicle data:
Skoda Octavia, year 2005, 2.0L TDI 16v "Pumpe Düse" engine with DSG transmission, engine code: BKD.

Mileage:
Engine: 270,000 km.
Mileage: 210,000 km
Turbocharger: 210,000 km.
remaining mileage: 455,000 km

Problem:

The engine stalls when maneuvering/parking. This happens regardless of whether the engine is cold or warm. It often occurs when the air conditioning is on. When the car is stationary with the gear in drive, the engine speed momentarily drops to about 600 RPM and then stalls. This doesn't always happen; often everything is normal when the car is stationary and when maneuvering. The car starts up without any problems.
"The error memory shows an intermittent, implausible signal for terminal 30, and a problem with the glow plug for cylinder 3. There's a brief puff of white smoke during cold starts, and it produces black smoke under load. However, I would say that this has always been the case."

Where should I start when troubleshooting?
The battery is new. I have the VCDS data ready.

Best,
Melanie

Hello.

Quote:

Terminal 30, sporadic implausible signal

= Power supply

If it only happens when maneuvering, meaning you're frequently turning the steering wheel, I would focus my attention on the ignition switch and the cables near the steering column.
You might be able to trigger it to turn off by shaking the corresponding parts.

Best regards, Rainer.

Okay, I continued trying and researching.

It also turns on even when the steering wheel isn't being moved. I've checked the cables, and everything seems to be fine.
It only happens when the air conditioning is on and only when the car is in gear. Everything is fine after about 70 degrees Celsius, and the fluctuations and stalling stop.

The fluctuations in speed are clearly audible, and it cuts out when driving straight forward and backward.

I hope someone has an idea of what might be causing this.

Best,
Melanie

Hello,

How does the air conditioning system's fuse blow? Do you have plug-in fuses on the battery?
I once had an issue with an Audi A3 8L where a faulty fuse box with poor contacts caused so many disturbances in the vehicle's electrical system that the engine control unit would intermittently reboot.

Best regards, Rainer.