[1784]

Hi
I have a 2006 xc70, 170 000 miles which was using a lot of oil. When I bought it it had had a new dpf fitted. All evidence seemed to point to turbo oil seals leaking by so I have fitted a new cartridge to the turbo with a friend who is a very capable mechanic.
Car runs great and seems smoother, however, when it gets warm it goes into limp mode and gives code 1507. I understand this is low turbo pressure. It happens when I take my foot off after a bit of acceleration.
Let the car cool a bit and it drives fine without clearing code but soon goes to limp mode again. My instinct is that it's something to do with the turbo actuator not closing once warm, is this likely? Do I neeed to have the new turbo set up in some way?
Thanks for your help, if you can
By the way, vanes were and are completely free moving with the turbo on the bench
Chris