Well, I had an engine warning light on my dash recently. The following codes came up;
4.2L V8/5V G 0010
P/N: 4D0 907 560 DB
Coding: 0007875, WSC: 31414
17546 P1138 097
Bank 2, mixture adaption air (add.): system too lean [static]
16558 P0174 228
Fuel Trim, Bank2: System too Lean [static]
These codes mean that there is vacuum leak somewhere in the intake system. I checked all of the hoses and found nothing. Eventually more codes came up which were the other bank now. I kept hearing an air noise towards the back of the engine. The crankcase ventilation valve (ccv valve) sits just under the "VW" sign on the center engine plastic cover. There is vent hole on the top of the ccv valve which was sucking a lot of air. My research found that this should not be so I removed and disassembled it. After disassembly, I found that the diaphragm was torn. This was my vacuum leak. I replaced the ccv valve and then cleared the code and it stayed gone. Here are some pictures of the old ccv valve disassembled.
Below is not supposed to be two pieces.
To remove and install the ccv valve, remove the two tubes that are connected to the two ports you see below. I threw away the hose clamps that were stock and replaced them with worm screw type. Works just fine.
This is a borrowed picture from Rock Auto showing the top of a new ccv valve. You can see the vent on top. This is where the vacuum leak could be felt. There should be little to no sucking happening from that vent hole.