Hello,Yo need to have the P2306 solved. It puts the engine into limp mode. The issue is usually caused by short circuit in one of the engine sensors (boost, pressure difference sensor on DPF, accelerator position sensor etc.) I suggest to disconnnect all of the sensors one by one, until ECU will start to show that disconnected sensors have interruption. This will indicate that sensor with a short circuit is faulty.
It is possible that the ECU wiring has been damaged during installation. So all of the engine sensor wiring should be carefully checked for short circuits as well.
Let me know if further assistance on this is needed, I am here for you.
Thank you for your answer, unfortunately we could not wait for it and took the van to the dealer on Thursday. They have sorted the engine lights but have not yet fixed the poor running.
When I asked my question, I thought there were someone there to answer instantly or rather within a few minutes, even hours. I did not think it would take 4 days to get an answer.
Thank you anyway for your answer but I am sorry it did not help.