Limp mode.

[youngsandy]

I've no doubt this topic has appeared here before. Christmas eve on the way to work the coil light came on on my 2009 2.0tdi CBAB engined passat (146000mls)and the car went into limp mode. Arriving at work and switching off I then restarted and lo' and behold no warning light.
So after work set off home no problems then 6 miles down the road coil light came on and back into limp mode stopped and started the the car another 3 times and everything went back to normal then coil light came on and the engine management light.
Anyways couldn't get anyone to look at it 'til the 4th. So local mech. takes off egr valve and cleans it (said it wasn't that bad) he said when he plugged it in the warning was for turbo boost cleared the faults and said everything was fine after a road test.
So I head off to work and 6 mies down the road the same story coil light and engine management light on and back into limp mode.
I took the car back today phoned the mech. to check on his progress and he says there is no vacuum at the turbo. I did ask him to clean the turbo boost sensor I don't know if he did as he wasn't there when I went to collect the car.
So does anyone know what the problem is, I don't have any codes the mech. did say that he couldn't get full access to the engine management computer.