Fuel gauge problem

[jd_hants]

A friend has an A8. When the tank is completely empty, the gauge still reads 1/4 full. But when the self test is done, the gauge needle does move to both extremities of the gauge.

Apparently the resistances of the senders does check with the spec.

Any ideas? I wondered if there was some kind of calibration or reset available within VAGCOM?

[PetrolDave]

There certainly is empty and full calibration adaptation channels for some instruments (e.g. the 8E A4), but I can't see anything on the Ross-Tech wiki, maybe worth contacting Ross-Tech to see if they know how to calibrate the gauge on your friends A8 (they'll probably need a full scan).

[Blue_Thunder]

The instrument test only proves that the cluster is working. Sounds like an issue with the fuel level sender.

[jd_hants]

Found some info about using VAGCOM to change the gauge needle 'Adaptation - Channel 30'. But it only says it allow the needle to be calibated +- 2litres!!!! Both senders return the correct resistances when empty and the correct combined resistance is available at the plug which goes into the cluster. Maybe the gauge is faulty itself or somehting on the cluster!