Zafira B z19dth boost issue

[cheese_za]

I need some help with a problem I am experiencing.

Car developed a slight turbo whine and at low rpm/low load. After googling I put this down to a leak at 1 of the gaskets on the turbo. Car was still pulling like a train.

Then one day taking a drive the car felt very sluggish/laggy (I thought it couldn't been a blocked DPF) and once I got on the dual carriage way I got check engine light and limp mode.

I am getting fault code P0234-5B Boost Pressure Control Circuit Positive Deviation.

I did have a brief look under the bonnet but am not sure what to look for. Can't see any obvious damage to hoses/vacuum lines.

Here is a link for live data recorded to trigger check engine light and limp mode.

Any advice would be great thanks.