I have a 01 a6 2.7t and im wondering what would cause my gas gauge readout to fluctuate so much? Example: 2 days ago i had 1/2 a tank worth of gas and i took a 50 mile trip and when i got home it was a little over a 1/4. Next morning i went to leave for work and i was in the red. Later that day when i was leaving work it was on empty (my trip was only a mile from my house that morning). So i stopped by the gas station on my way home and put 3 or so gallons in my tank and my gauge still said empty. So i left a little later to go to the dentist and on my way home i stopped by the gas and put about the same in the when i started my car my gas gauge said half full. What would cause this?

 

My old lancer use to do that... if its an electronic read out it could be the readout malfunctioning or there is a sensor or some cars have a small float in the gas tank that reads the level... this could either be bad and needs to be replaced or is just dirty from the impurities in the gas...if its bad take it to audi and if its dirty then a simple gas treatment will clean it up for you... I tend to use a gas treatment once every 10 FULL tanks. Say full cause i dont consider putting a couple dollars fulling up... try that first and see if the problem clears up... then if it persists then take it to audi.

 

With that said does anybody know what type of gas sensor is in a 01 a6 and how would i get to it or how to examine it?

 

not sure on the type... check with your local audi dealer or auto shop... as for checking it.... its probably located in the gas tank... i had a fuel pump replaced in my 95 bonneville a cpl years back... you have to ciphen the gas out of the tank... as much as you can.... then drop the gas tank and check inside it... if it is welded onto the body you have to run the car after it is ciphened until it dies to ensure all the gas is out then leave the tank open for a while to let the fumes out... the las thing you want is a gas fire under your car... after its checked reverse the process to put it back together.... I strongly reccomend taking it to a certified shop as they are insured for such mishaps and have more experience doing it. but first just try a stron gas treatment... it might clear it up for you and save you the trouble.

 

Mine behaves a erratically when it gets below 1/4 tank. Problem solved by just filling it whenever it gets to 1/2 tank. The guage has never been accurate, being overly optimistic for the first 1/2 tank (200-250 miles) and then drops like a stone to 1/8. I usually get 380-410 miles per tank on the highway, so I've learned to go by miles vs the guage.

 

Check to see if there are any service bullitens on your car.
I had this issue on my 98 and had the dealership fix at no charge.
Good Luck1998 AUDI A6 Technical Service Bulletin

HOME » A » AUDI » A6 » 1998 » 610267
NHTSA Item Number: 610267
Service Bulletin #: 0001
Replacement #:
Vehicle/Equipment Make: AUDI
Vehicle/Eqipment Model: A6
Model Year: 1998
Mfg Component Code: 090000 FUEL SYSTEM, OTHER
Date of Bulletin: 2000-01-07
Date Added: 2000-04-24
Summary: SUBJECT REGARDING AN INCORRECT FUEL READING ON FUEL GAUGE (ERRATIC, STUCK ON FULL OR EMPTY). *TT