Fehlercode P0299 Citroen C5 R 125 KW (ACU)

[cit-rotti]

Error code P0299
Occurs both temporarily and sometimes as a permanent error. Can be deleted - but keeps coming back.
VF7**************[VIN obfuscated, can be read by forum staff]
The vehicle does not go into emergency mode - no loss of performance recognisable and no fault light comes on.
Now to my problem. I realise that this error can have many causes, but perhaps the error code and the following description can help me narrow it down.

The model has 4 solenoid valves and lots of vacuum hoses for the turbo control - is there any recognisable damage to the turbo control or other leaks?

Or even turbo damage with jammed adjustment or or or...?
I am grateful for any information and help.

Greetings Wolfgang

[PaulC5]

Use a code reader that shows live data and look at the MAP sensor which shows the turbo boost. I had this code a few times over several years on our C5 but it did not put on the engine management light. I found the MAP sensor values were not changing much as the accelerator pedal was used. I found the MAP sensor was bunged up with oil so replaced it. The code did not come back but after a couple of years has appeared occasionally so the sensor might be bunged up again but I have not checked or it could be something else.

[GiveMeABreak]

The only info for this is Turbo pressure regulation: Pressure below reference value and I won't bother with the descriptor as the list of possible suspects is as long as my arm and not really helpful.