I have a 2003 audi a4 and am having a problem when filling up. I can only fill the tank up to 3/4 tank then it clicks off like it is full. What could be causing this? I'm stumped anyone with any ideas please help its very annoying!

 

Are you sure that your tank is not full? Let the tank empty till about first red line (1/8 full) then fill up until pump nozzle clicks off. You should have pumped about 12-13.5 gallons to fill (I'm assuming you have a 3.0 Quattro). If the gas pump only shows 9-10 gallons then there is something going on with the chambers of your fuel tank (I don't know what, nor could I imagine). If the gas pump shows that you pumped 12-13.5 gallons then that means your 16gal. tank is full and the problem is with your fuel gauge on the dash or the level sensor in the tank.

The reason I'm saying this is because I have this exact same issue on my 02 3.0 Q. The gas tank is full, but on the dash it's shows 3/4 full. I just learned to live with it. No biggie. If you have the same issue you will notice that after you fill the tank your gauge will stay on 3/4 for at least 45-75 miles of driving until it finally starts to move to 1/2 full.

And you thought you were getting great mileage!!

Hope this helps

 

I guess the 1.8T might be different in this regard, but IIRC the spec says it's a 17.4 gallon tank. Even if it was 16 gallons, at 1/8 full, you should have to fill around 14 gallons to fill it. (My experience has been that at 1/8 full, I'm usually filling 14-15 gallons, which coincides reasonably well with a 17.4 gallon tank.) I don't know what could cause the OP's issue, but it doesn't seem right to me.

 

1st of all make sure you're actually getting a full tank or 3/4 of a tank. If you have a Quattro it takes 15.X ammount of US gallons, if you have CVT is 17.X US gallons. If the coding is missmatched you could be reading the amount of a CVT in a Quattro and viceversa, causing your erroneous reading at the gauge but a physically full tank.