passat 2.0tdi 170 bhp problems

[redI]

hi guys i am new to this forum, i have had the new passat 2.0 tdi 170 break passat for a couple of years and it has been problem free, regular services and properly maintained, but for the last few weeks it has been running powerless there is nothing there when u put your foot down or if there is it is very delayed. last week i was on the motorway at bout 70mph when the coil light started flashing and the car started running in safe mode i had someone come and check it out and the light was reset but the fault came up as the turbo underpressure. It has been a couple of days since then and i have been driving the car on long journeys and the light has not come on again but it is still running flat. Could anyone on here suggest what it could be or has anyone else had a similar problem? i was told that it could be the turbo or a certain valve which i cant remember the name of but the car has only done 90,000 miles could it be the turbo so early on or could it be something else? it looks like the car will have to pay a visit to vw at the moment but any help from anyone on here would be much appreciated.

thanks.