Hi,

I'm new to the forum and hope that I've come to the right place.

My car details are the following:

Audi A4 2002 1.9 TDI
194,000 miles
Company car for 155,000 of those miles on UK roads.
Very well maintained and serviced (just fully serviced last week actually)

The problem is that she overboosts around 70MPH and goes into limp mode. It only happens at this speed which I find odd. I've researched this and some say that the MAF sensor could need replacing or cleaning but I don't have tools to get it out and my mechanic assures me it's not the MAF sensor.

The computer throws the error - 17965 - Charge Pressure Control: Positive Deviation.

So far the mechanic (not an audi dealer) has replaced 2 vacuum hoses that had cracks in them which didn't solve the problem. The next step is replacing some sort of valve but I can't remember the exact name of it. If that doesn't work the mechanic says next step is to change the ECU which from my research looks damn expensive

I'm just wondering does anyone else have a similar problem and would know why is it only 70MPH + that this issue occurs, no matter what revs are on the clock.

This problem has occured very seldom in the last 2 years but only recently is much more persistent. For the last 2 years I've driven the car very easy which I thought would help me prolong it's life (because it has high mileage) but apparently from what I've read, the vanes in the turbo can get stuck. If its stuck in the open position this could cause the issue. The last year or so I only do about 4 miles a day because my work is very close so was wondering might this have sped up the issue because its not getting driven enough and the turbo vanes may be getting dirty. I do however make sure shes fully heated up before I kill the engine each morning.

It looks like parts of my research contradicts what I'm being told by my mechanic (who is reputable) so I'm wondering would it be worth my while getting the MAF looked at / turbo dismantled and seeing if there's a problem with the vanes before I replace the ECU? How much of this can I do myself I wonder,. provided I have the correct tools?

I don't really have much $$$ to be putting into this unfortunetely so would appreciate any helpful work arounds / cheap jobs that any one could throw my way.

Thanks for reading and sorry for the long post. I just wanted to give all info available.

Thanks