I am having the same exact problem with the same code. I lose boost and go intolimp modewhen i drive on the freeway for too long, or at random intervals. I changed my MAF yesterday and that didn't seem to help. I'm going to switch the thrust sensor now too. also, I'm going to fully inspect all hoses. It's been hard to lately because it's cold outside and my garage has an old car in it right now.

 

thrust sensor is what regulates boost... it is right behind your driver side head light..... i will take pix tomorrow if needed

 

ok so i got this code a couple days ago, it claims that the left bank is running lean, my mechanic suggests an 02 sensor. Ill probably change that, but you guys are saying i should also check the thrust sensor and the maf sensor? I dont have a boost guage so im not sure if im losing boost, i have only had the car for a few weeks but i would like everything to run smoothly before i start into my modifications. thanks guys. how much should i expect to spend replacing these parts? is it a job that i would be able too do?

 

when i had this code forever ago it was because i had a vacuum leak in one of the lines. Chaos basically gave u all the possibilities.

 

P0170= dirty car code, and or low altitude code. I have had the same code coming up intermittantly over the past 5 months. Finally i just got tired of deleting the code and seeing it pop up, so i just got used to driving in limp mode. Well last weekend i drove up to the mountains. CEL went away and the car ran like a dream. Came back down and it came back on. (hence low altitude code) then three days ago i washed the car and tada. CEL off again and has stayed off and is running like a dream. Im telling you. All the car needs is love. A little snow for the Quattro, a clean exterior and shes good to go. you could also try giving it a hug.

in all seriousness the point of this is that code could be so many things it may as well be one of those. good luck man, im still trouble shooting.