This is an odd one....but trust me this is 100% true.

After I drive my car for any length of time and it warms up, when I go to park it I can hear this "honking" sound coming from the passenger side rear wheel well. The honking isn't constant....just on and off, and it isn't extremely loud by any means but it is rather annoying. This lasts for quite a while but once the car is cooled down it stops.

My original thought was that it was somehow tied to the brake caliper - as if it was cooling down and retracting one of the pistons. I also thought maybe it wasthe muffler in thatarea and thenoise was simply expansion and contraction from the heat. Therefore, in an effort to get a better idea of the source of the issue I jacked up that corner of the car and removed the wheel to get my head in there and get a better idea of where the noise was originating from.

Well, as some of you probably already know it wasn't the brake and it wasn't the muffler. The noise was actually coming from one of the two lines that head to the gas tank. Once I figured this out (and after slapping myself on the forehead for not thinking of it sooner), the first thing I did was to remove the gas cap. When I did so, I could hear a significant sucking of air (normal for most cars) and then a lot of gurgling of fuel. That resolved the honking sound, so I know what it is tied to but I still can't see to figure out how to get it resolved. If I loosen the cap after each drive, the sound will go away, but if I immediately tighten it again the sound will come back in a few minutes (although at a much lower sound level).

I thought perhaps it was a faulty gas cap that wasn't letting in any air and thus was creating a vacuum - and when the fuel is pulled out of the tank the "honk" is created by the air trying to get in to the tank. So I visited by local Audi dealer and $22 and change later I had a replacement cap. I installed it and a few days later after a drive I noticed the honk again....so obviously the cap was not at fault. I still think my theory of the vacuum effect is accurate, but the cap itself is not the source of the issue.

Anyone have any ideas?

 

Nobody has any input on this one?

 

First i would run a vag com for any stored codes. you may want to check the fuel tank venting system. maybe a vent line is kinked of the filter is clogged. do you get any oder of gas?

 

Had it in for a ABS indicator light and my local indy shop checked for codes....nothing related to the tank or fuel system.

I don't have any fuel delivery problems, but I suppose it is possible a vent line is kinked....although I don't know how that would happen exactly. I don't get any odor of gas until I open the fuel filler door at which time the odor is fairly strong.

This is just one of those things that baffles me. Can't see anything wrong and short of pulling the entire tank and examining everything I don't know what my options are.

 

I have the EXACT same issue and it has had me confised for two years. I have no related codes via VAG-COM either. I've been leaning towards a fuel pump issue as my car runs very rich on startup.