Hello, i have a problem, for some reason i filled up a full tank of gas and that was saturday last thing before i headed home, sunday didnt use the car, and monday used it to work, from work, and hangout, and today to work and from work, checked my tank meter, and it says that i have half a tank of gas left, and i look at the amount of miles i used up since i reset the meter, and it says that i have a half a tank and used up 56miles...how is that possible? i put premium in the car, the most expensive one, and fill up from Mobile gassstaion. I have a 1999 Audi A4 2.8 Quattro

please help someone

 

sending unit is bad in the tank. happens to alot of A4's. mine fluctuates a bit, but is always accurate when i get down below quarter tank.

 

so what do you mean exactly? and how can i fix it?

 

is there a gas leak in your car, or is your gague messed up?

 

The sending unit in your tank, its the thing that says how much gas yo have left may be going bad, it sits in gas all the time, will show in correct info but as long as you dont run out of gas when it says half full then not too bad.

 

well i dontknow, because i dont think i have a gas leak, because under my car there is no gass so i dont thin its a gas leak...as for the gague i have no idea what that is and where it is lol, im a noob...and as for the sending unit, can that be replaced? and how?

 

if you had a gas leak that took a half a tank of gas in 2 days you'd smell it.
sounds like a gague issue. try driving the car around for a while with a gas can in the trunk until it runs out. or not even that far. If you're going as far on a tank of gas as you normally do then the problem is that your gas gague is misleading you. worse things could happen. just reset your trip counter and use that as your gas gague from now on.

 

Sounds like the sending unit for the gas gauge. As people above have said, it sits in the gas tank and eventually fails.

Go to a gas station and fill your tank. You will probably find that you only used 2 or 3 gallons. If you need half a tank, and you don't smell gas leaking it is likely that the gas pump clicked off earlier when you used it and you didn't fill it up.

 

Same thing happens to me occasionally. Fill the tank up, and the next morning it shows only 1/2 tankfull left.

I think i've pinned it down to filling up when I'm close to empty. Is that what you did?

If i fill up before i have 1/4 tank left, i don't get the problem.

 

Yea same thing happened to me. The first time it happened I complained to the gas station attendant because I thought I paid for a full tank of gas and it only filled me up halfway. Then later I found out what was wrong and felt bad. But anyways I found this post in the forums that has the part number for the sender unit you need and how to fix it if you do it yourself.
https://www.audiforums.com/m_20295/tm.htm