Air leak, faulty boost pressure sensor? Start with visual inspection of all hoses between turbo and throttle. Follow with smoke test.

 

Thanks.will definately try that.

 

I had what may be the same error (P0299, underboost). For me, it seems to have been related to a crack in the intake "batwing" where it joins the turbo or a section of the air intake routing from the front of the car to the airbox being disconnected (not sure which, since I fixed both at the same time). For many people it's the turbo actuator or split/punctured air hoses in the turbo. There's lots of good info here: Crack in plastic batwing/t intake assembly - could that...

 

My mechanic finally solved the problem.he said the inlet manifold had gone bad and he changed it.he also changed the egr valve.now the car is back to its full power again and no more limp mode.l am enjoying it.