Vehicles with front wheel drive:

Sender for fuel gauge is located below the floor cover of the luggage compartment.

Unscrew cover for connector flange below the luggage compartment carpet.
NOTE: To do so, remove luggage compartment floor on the Avant.

See CARGO AREA FLOOR TRIM AND SUPPORTS (AVANT), REMOVING AND INSTALLING .
Carefully disengage and disconnect 4-pin harness connector (arrow).

Fig 1: Disconnecting 4-Pin Harness Connector (Front Wheel Drive)

Courtesy of AUDI OF AMERICA, INC.

NOTE: Terminal assignment for vehicles with front and all wheel drive is identical.