Fold back or remove the rear bench seat. Fold back the trim under the rear seat. Rotate the fuel level indicator sensor cover in the direction of the arrow and remove the cover.
Disconnect the electrical plug connection "arrow" on the blind flange.
A/m before 04.2002
To measure resistance, connect the multimeter to contacts "1" and "2".
Check the resistance value depending on the fuel level in the tank.
1) tolerance ±5 Ohm.
2) Due to the greater deflection of the float lever, the value is achieved only when the sensor is removed; value with the sensor installed is approx. 58 Ohm for "empty" or approx. 287 Ohm for "full".
A/m since 05.2002
To measure resistance, connect the multimeter to contacts "1" and "2". Check the resistance value depending on the fuel level in the tank.
1) tolerance ±5 Ohm.
2) Due to the greater deflection of the float lever, the value is achieved only when the sensor is removed.
[The original source of the article can be found on the website: audimanual]