Vacuum Leak - P0171/P0507
 

I am quite the noobie when it comes to automotive repair; I know trucks and especially military vehicles, but never a European car like my wife’s Audi. Right now I face the problem of a vacuum line or something of the like. I am getting the error codes:

P0171 - System too lean; low fuel pressure or volume; Probable cause: 1. Faulty HO2S, 2. Large vacuum leak, 3. Faulty MAF sensor
P0507 - Idle Air control system RPM higher than expected; Large vacuum leak on engine: Probable cause 1. Throttle plate misadjusted or damaged 2. Faulty IAC valve

Some back ground: Weather has gone from moderate to sub-temperatures; the car is parked in the garage every night, in a parking garage during the day, driven 40 minutes total per day. It is a 2007 Audi A4 2.0T with 82,000 miles.

I am attempting to locate, the vacuum tubes but I am not quiet sure what I need to look for. All the places I look online are kind of cryptic and don’t do a great job at describing what to look for. If anyone has a good large res explosion chart of the vacuum tubes, Throttle plate, MAF sensor it would be of great help.
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If anyone has an idea as to what I can do to fix my problem, I would be indebted to you.

Thank you.

Those codes could mean a bad pressure regulator valve (PCV). It's a common problem on these engines. Same codes I had, and others on this forum.

Pull off the plastic engine cover and you'll see it. Looks like this:
http://i25.photobucket.com/albums/c5...y/DSCF1138.jpg

I'd double check your cam follower.

Were is the Best Place to Buy the PVC Valve ?

got it at dealer so you will get a latest version of crank case pressure regulator.

Try to pull oil filler cap while engine at idle. If it is so hard to pull the cap, the crank case pressure regulator valve is the most likely problem.

where is this crank case pressure regulator valve located?

what does the cam follower have to do with this?

Crank case pressure regulator valve is mounted on valve cover and has two hoses connected to it.

Crankcase pressure regulator valve
 

Which one of these is the updated one, http://www.partsgeek.com/catalog/200...ent_valve.html . I'm having the same idling issues and I'm not sure if the regulator valve should be blowing air out of it at such a high sound. It only happens when I am parked.

there is a tsb on that,also on flap motor,possable fuel pressure ck valve too,give your vin# to your dealership and see what happens,should be free under warrt.,hope that helps,