cm570 turbo overspeed fault

[pazz]

Hello all. I have a cm 570, @600, in a 2007 cabover which is giving a turbo overspeed fault [595] and derate every time you put the boot in. I'll go back a bit, probably about 12 months ago it would give random check engine lights but wouldn't derate, the only effect was the engine brake would have a 2 -3 second delay in activating. Can't remember the code now but was related to the combo sensor which is about $850 here, so put it off as it wasn't a big deal. Eventually it got more frequent so I got a sensor of ebay shipped from China for $40 and it solved the problem for about 5 months. About 2 months ago it started again however this time would derate. Once again, can't remember codes but were related to combo sensor again so bit the bullet and got a genuine part. 2 weeks ago my turbo failed. Snapped shaft and sent oil through engine. Started to run away but fortunately was pulling over and was in gear so stalled it straight away. Had to get towed to a shop where they replaced turbo and intercooler, as it was cracked. Since then it's giving fault 595 every time you put the power down. I've driven it from the shop to home, about 1000km, where it sits now until I can sort it out. I've fixed the boost and exhaust leaks they left me with and removed and cleaned the combo sensor as it did have some oil on it but to no effect. Looking for any advice.
P.S engine sounds fine and pulls as hard as ever, until derate, post turbo failure. Also have access to insite.
Thanks
Matt