Hope there is someone who may help. Im first timer on forums like this so please be patient.
I have just bought privately an A4 avant 2007 2.0tdi 140 with 74,000 miles.

Worked fine for the first week, then when cruising at about 80mph 2,500 revs the engine went into "limp mode" allowing very limited acceleration. Turning the engine off appeared to reset and all was normal again until the next time. No engine fault light appeared. On subsequent journeys this has occured again and the engine warning light now comes on, but am able to "reset" limp mode by turning off ignition.

I have now taken to a audi specilaist garage who stated might be the turbo as this was the fault code which came up on diagnostics. They stated this could however be a number of faults and not the turbo itself. They replaced the turbo booster sensor but this lasted 10 minutes before the engine again went into limp mode.

Becoming increasingly frustated as the garage is now saying new turbo needed at cost of £1300 approx. Im concerned that they are blind guessing and the outlay may not fix the issue

Has anyone come across this problem before?

Im not a mechanic but I cant see how a turbo is needed when it works perfectly well unless cruising on motorway. Is it unusual for a turbo to malfunction after 70,000 miles.

Any help much appreciated

 

This sort of thing happens to turbos in this engine. What fault is registered, about the pressure being too low or too high?