So... my check engine light has been coming on intermittently and the turbo turns off sporadically. It seams to engage random while the light is on.

I plugged my laptop into it and pulled these codes:

17956 - Boost Pressure Regulation Valve (N75): Open Circuit
P1548 - 35-10 - - - Intermittent

17536 - Fuel Trim; Bank 1 (Mult): System too Lean
P1128 - 35-10 - - - Intermittent

I do have some octane booster in the tank, but I've never had a problem with it before. Without it, the motor seem to knock and will not exceed about 4500 rpm.

What do I do to fix the code and make it run correctly? I dunno a whole lot about Audi engines or turbos, but I'm mechanically inclined.