Wanted to give a play by play of this one. Yesterday I was driving up the big hill in Randolph in my 2002 VW Golf TDI, and my turbo boost went out. I tried stopping/restarting the car (which has worked in the few times in the past) but... nothing at all. So whatever is is pretty shot. As far as I can tell, the car has absolutely no turbo boost at all (I can hear no whistling and feel very little power). The car is technically drive-able but has a hard time keeping up with traffic. Reminds me of my old '81 diesel rabbit (NA).
I pulled the codes when I got home, and (among the massive list of other known issues) I saw a new one:
17964 - Charge Pressure Control
P1556 - 35-00 - Negative Deviation
So at this point I'm thinking that it's one of the following:
- Boost leak (unlikely, since I probably would have heard it)
- Problem with the VNT actuator (misadjusted or stuck)
- Vacuum leak (due to a worn out hose)
- Bad N75 solenoid (this is the interface between the computer and the vacuum)
Stay tuned as I reduce the haystack down to a more manageable size, in search of the needle causing this problem.