Fuel Level Sensors, Removing and Installing

NOTE:
- Follow safety precautions and rules of cleanliness when working on fuel tank.
- Before both fuel level sensors are removed, check them with a multimeter (Fluke 83 or equivalent) to see if their resistance values are in an appropriate range for the level displayed on the fuel gauge. Since the fuel level sensors are connected in series, the two resistance values must be added together when checking them against the fuel gauge reading.


Fuel tank identification
The Audi A8 is equipped with one of two fuel tanks, with fuel capacity of either 80 liters or 90 liters. Check the first digit in the production number to tell the difference between the two tanks.







The production number is stamped on the bottom right-hand portion of the fuel tank.
- First digit "0" (e.g. D-ET 000 001) = 90 liter fuel tank
- First digit "6" (e.g. D-ET 600 001) = 80 liter fuel tank

- Disconnect electrical connections on left- and right-side fuel level sensors.
- Measure sensor resistance individually, then add values together and compare with specified values in table.

90 Liter Fuel Tank:

80 Liter Fuel Tank:

Left-side fuel level sensor


WARNING!
Fire hazard. DO NOT smoke or work near heaters or have anything in the area that can ignite fuel!


Removing


CAUTION!
Fuel tank must be no more than 2/3 full. Remove fuel if necessary using an approved fuel cart.


- Disconnect battery Ground strap.
- Remove fuel tank sensor cover located under luggage compartment trim.
- Disconnect fuel level sensor connector at fuel tank.







- Use special tool 3217 to open lock ring.
- Carefully remove fuel level sensor.

Installing


NOTE: The fuel level sensor must be installed so that the bracket holding the wiring for the left transfer pump is pushed down, pushing the pump to the bottom of the fuel tank. If the fuel level sensor is not installed in this way, the left cavity of the fuel tank will not completely drain and approx. 10-14 liters (2.6-3.7 gallons) of fuel will remain in the fuel tank.







- Install left-side fuel level sensor.
- Fuel level sensor -2- must be correctly installed in bracket -1-







- Check by looking into fuel tank from side as shown (arrow).

If OK:







- Press fuel level sensor into opening, and turn lock ring so that both arrows align with each other.

Right-side fuel level sensor

Removing

- Remove cover for fuel level sensor and fuel pump, located on right side under luggage compartment trim.
Wire and connectors may remain connected.







- Using special tool 2012A, open cover by turning clockwise, then remove compression spring below.







- Using pliers, carefully lift sensor and disconnect electrical harness connector.
- Remove fuel level sensor.


NOTE: When removing and installing the sensor, make sure that the wiring is not damaged.


Installing
Installation is the reverse of removal.