bbottlinger

I have an Audi a8 Quattro that the fuel level indicator does not read "full" when I fill the tank. I have had back to the dealer who on two occasions has said that they cannot duplicate the problem so they cannot help me. Can you offer some help/ides?

Mortem76

I faced something similar (in my case, the gauge said full when only 60 liters in the tank) and it was related to Fuel Gauge Sending Units.
In my A8 1996, as the tank is split in 2, there are 2 of those.
Not sure your A8 use the same models or not as this is a FL that you have, but below are the P/N:
- Fuel Gauge Sending Unit (Left):
Audi #4D0919051J
- Fuel Gauge Sending Unit (Right):
Audi #4D0919051C

For my case, I didn't have to buy new ones (so far) as my mechanic thinks he can save them by cleaning them and re-calibrating them. I should know tomorrow (or maybe next week) if he was successful

Hope it can help

bbottlinger

Thanks so much for your thoughtful/helpfull response!

Mortem76

Welcome. I will have my car tomorrow (Saturday) so I can check if cleaning/recalibrating worked for them.
And let us know if the info I provided is relevant for your issue

twentysevenlitres

I had always thought that 4D0919051J (left side of tank) was the low level sensor, but I was corrected at one point that the fuel gauge does take average reading from both sensors. However the left sensor can't possibly measure the full tank as it doesn't have enough range of movement.
The right sensor is a free moving float sensor and will measure the full tank. So if you have a problem with a the tank measuring full, I'd goglooking at the right side sensor.

Mortem76

My mechanic checked both and so decided to clean them all and recalibrate them.
I had my car last weekend and said me he fixed it. I will now have to take my car for a trip with a jerry-can in my trunk and try to empty my tank to see if it is working fine. I should make my full test end of next month when I will have some free time