Hi there, I have an Audi A3 2004 SE TDi 140bhp I am experiencing power loss whilst traveling at approx 80+ MPH on the motorway. The turbo cuts out and it appears to go into limp home mode, I pull over switch the engine off then back on again and it works fine, no power is lost in accelerating up through the gears to get up to 80+ were the problem is occurring. This problem doesn't happen all the time but it is becoming more frequent and means that long distance traveling is out of the question. Sometimes the engine management light comes on and other times it doesn't (power is just lost) - the engine management light goes off within a day or two if it does come on. I have taken the car to the garage where it was hooked up to the computer and it threw up the following codes -audi code 16683. Boost pressure reg control not reached and european code po299 . It was also put through some tests to see if the actuator was working correctly - which it was. This feels like a problem with a sensor as it is corrected by switching the car off then on. I have read about this problem online but I haven't read of a resolution as yet. Hope you can help. Oh and the car has done 99K with full service history, was previously owned by a fastidious Audi mechanic. Thank you in advance for your help!!