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  1. #1
    Reverse Gear

    Join Date
    May 2012

    Leaking Fuel Cap


    can anybody diagnose this problem? My A4 is leaking small amounts of diesel from the fuel filler cap. I replaced the cap with a genuine Audi cap but it has not solved the problem. The inside of the cap is always wet when I remove it (my previous cars were always dry) and there is a visible wet patch beneath the cap on the plastic surround by the drain hole. When I have fueled up this often spills out on the back wing, even when the tank is only half full!?

    Is this something to do with venting of the fuel tank? I spoke to my normal Audi specialist (not dealer) who said he had never come accross it before.

    I have done some searches but I cant see anyone with the same problem.

    Any help appreciated.


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  3. #2
    swarcup's Avatar
    5th Gear
    Breakout Champion

    Join Date
    Sep 2009
    beverley,East yorkshire
    mine does the same although ive never thought it was a problem till now, do they all do it?
    2.5tdi Avant Q S 180 - 19" RS6 reps - chrome mirrors - ambient light package - cruise and dis retrofit - chrome side repeaters - front sline lowr conversion with cupra r splitter - rear lower valance with twin cut outs and exhaust tips - rs4 rear antiroll bar - puddle and footwell lights - sline door blades - fully colour coded - b8 autodimming mirror on custom window adapter - geuine aero wiper upgrade - genuine heated mirror upgrade

  4. #3
    Reverse Gear

    Join Date
    May 2012
    Not sure but I've only noticed this on the last two fill ups. Can't be much fuel as it hasn't had any noticeable affect on mpg. Just don't fancy my hard earned diesel splatting down the back of my car.

    Do you notice it on the rear wing?

  5. #4
    Reverse Gear

    Join Date
    Jun 2013
    I have the same problem on my A3. I noticed the fuel on the rear panel a couple of times then saw that the inner cap was sludged up. I cleared it out with a cocktail stick but it is still happening. When I wash the car water sits in the inside of the filler cap area and doesn't drain, which I don't think is correct.

    any ideas?



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