If complaints are made that the fuel gauge of the above-mentioned vehicles is inaccurate or faulty in any way, a possible cause for this error is the fuel level sensor (fuel feed unit).
Possible contamination of the resistance of the fuel sensor on this component (the unit) can cause the malfunction.
The fuel gauge does not correctly indicate a full tank.
In order to run a check on the fuel feed unit, the rear seat has to be dismantled. It is then possible to remove the fuel feed unit from the fuel tank and to test its electrical functioning.
The float arm is also to be checked / visually checked for accurate functioning (it could be bent out of shape).
If any deviations from the norm are detected, the fuel sensor (fuel feed unit) should be replaced by the car manufacturer's modified version.
Fuel level sensor:
Spare part no.: 16.146.761.353
Important safety note
Not helpful at all