Please post the pictures you have . I can't figure out how dirt can clog a new car. Did the dealer say anything about how to prevent this from happening? Previous threads have talked about some part to block water from the hood from dripping into the intake tube.
First time trying to upload pics, so...
1. Opened filter box and this is the first thing I saw...wet at the bottom 2-3 inches. Remember, I just got this car brand new from the dealer...delivered with only 134 miles on it. All I did was put it in my driveway.
2. Removed filter and found dirt/sand in the box. Cleaned everything out and tested by pouring some water around the drain...drained out no problem. This is the drain that has a tube hanging down from the box...the end of this tube has a screen in it.
3. Used an old t-shirt to absorb water from the inside of the inlet tube...didn't really work.
4. Stuck my hand in the tube, felt the drain plug immersed in water/sand mix. Crawled under the car, found the drain plug and pulled it out. Yuck...make sure you keep your eyes and mouth shut if you do this. Luckily, I've got fairly long arms and was already kind of off to the side when it came out. I almost got slimed pretty good. Flushed and dried the tube repeatedly until I was sure it was clean and dry. Put everything back together, except for the plug.
5. I think this is the part in question (P/N 7P6129609A). As you can see, the intake pipe is basically shaped like a p-trap under the sink. Couldn't find a separate number for just the plug.
Based on the way the plug is constructed, I agree with others that the dirt is coming in from the air inlet, not backwards through the plug from underneath the car as you drive along through dusty roads or dirty water. (I haven't confirmed whether the dirt and water is entering while driving, parked or both.)
For now, I think it will be all right to leave the plug out since I won't be driving through any deep water. I'll see if I can get VW service to show me how they would put it back. That way I can remove it for cleaning as part of regular maintenance (if necessary). I may be able to get away with just flushing it out periodically from the filter box side (as others have suggested).
BTW, the screened end of the drain tube from the air filter box drain hangs down much lower than the plug that's in the inlet tube.