[Flash635]

Do you have a VNT? If so,⁹check that for blockage too.
As for what should be cleaned: I just pulled my turbo to do a cartridge change because of leaky seals so I had a look on YouTube for clues and tips.
I saw one video where they cleaned and flushed the entire inlet tract then media blasted the valve ports. I don't know what media was used, I think it was in Russian.
The ports were very gunky.

The thing probably sang like Pavarotti afterward.

 

[Flash635]

Sticky VNT would also cause boost codes if it were the issue.

Yeah, it's just that generic " something is wrong" code which in my case turned out to be the water pump.

I guess a bit of soot is OK but I've also seen them gunked shut.
It's a good idea to check them.

 

[Flash635]

Can you please share this code with us.... I've never seen a "something is wrong" code that was fixed by replacing a water pump. Would love some education today.

I don't remember the code number but it indicates that the VNT actuator solenoid is faulty, few different things set it off.

In my case the water pump was leaking into the crankcase as they but wasn't emulsifying with the oil, instead the water was being sucked up by the PCV and into the intake.
Luckily it didn't hydrolock but at least one cylinder showed too much pressure causing a limp and throwing the code.
It's the same code that gunned up nozzles or a defective vacuum actuator or a bad vacuum hose will throw.

 

[Flash635]

Yep. Tested everything one a*t a time and believe me when I say that going after the water pump wasn't a decision made lightly.

I was impressed by the number of things that are revealed by using VAG Com but that particular area is pretty vague.