Zafira C CNG P2279

Engine A16XNT 1.6L Turbo 110kW

No way that I can solve this problem:

P2279 Turbocharger pressure not plausible

It appear IMMEDIATELY only running with CNG.
It does not appear if it run on gasoline (benzin).

With P2279 the engine is in limp mode.
And customer angry.

* CNG injectors are not responsable. ( 4 new, not OEM )
* Air Pressure sensor on intercooler pipe is not responsable. ( 1 new, OEM )
* CNG sensor on CNG tower placed to the left of engine bay is not responsable. ( 1 new, OEM )

Please help.
Thank you.