Fuel Supply System Audi A6 С6

Safety precautions

The following steps should be taken before beginning work on fuel supply system

1. Open fuel filler flap briefly and then close again.

When removing and installing components from full or partially full fuel tanks, the following must be observed

1. The fuel tank may only be partially full. How much fuel can remain in the fuel tank may be read in respective work description. Empty fuel tank if necessary --> «Fuel tank, emptying»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-tank-emptying) .
2. Before starting work, switch on exhaust extraction system and place an extraction hose close to the installation opening of fuel tank to extract escaping fuel fumes. If no exhaust extraction system is available, a radial fan (as long as motor is not in air flow) with a displacement greater than 15 m 3 /h can be used.
3. Prevent fuel from contacting skin! Wear fuel-resistant gloves!

Note the following when removing and installing fuel tank

1. Fuel tank must be empty for weight reasons. Empty fuel tank if necessary --> «Fuel tank, emptying»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-tank-emptying) .

Rules for cleanliness

When working on the fuel supply/injection system, pay careful attention to the following rules of cleanliness

1. Thoroughly clean all connections and the surrounding area before disconnecting.
2. Place parts that have been removed on a clean surface and cover them. Do not use fluffy cloths!
3. Carefully cover over opened components or seal, if repairs are not performed immediately.
4. Only install clean components: Only unpack replacement parts immediately prior to installation. Do not use parts that have been stored unpackaged (e.g. in tool boxes etc.).

1. When system is open: Do not work with compressed air. Do not move vehicle unless absolutely necessary.

Scheme 1

1 - Bolt

1. 23 Nm

2 - Suspended mount

1. For exhaust system

3 - Carrier plate

4 - Fuel line

1. From fuel filter to engine
2. Do not kink
3. To disconnect, press release button on connection piece

5 - Vent line

1. From EVAP canister to Evaporative Emission (EVAP) Canister Purge Regulator Valve N80
2. Do not kink
3. To disconnect, press release button on connection piece
4. Clipped in on fuel tank

6 - Bolt

1. Serves to secure fuel filler neck and Ground (GND) connection - 11
2. 23 Nm

7 - Overflow hose

1. Hooked onto wheel housing liner

8 - Rubber gasket

9 - Gasket

1. Replace if damaged

10 - Cap

1. Attached to tank flap unit with fastening device

11 - Ground (GND) connection

1. For discharging electrostatic charge
2. Installed location «Installation position of Ground (GND) connection»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system)
3. Ensure connectors are securely seated and wiring is fastened with bolt for fuel filler tube - 6
4. After installing, check electrical connection of metal ring at fuel filler tube to a bare area of chassis using Ohm meter - Specified value: approx. 0ohms

12 - Vent line

13 - Vent line

1. To EVAP canister

14 - Fuel tank

1. Removing and installing --> «Fuel tank with attachments, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-tank-with-attachments-removing-and)

15 - Securing strap

16 - Spreader clip

17 - Bolt

1. 23 Nm

18 - Heat shield for fuel tank

19 - Nut

1. 2 Nm

Scheme 2

1. Route Ground (GND) connection (Scheme 2)
2. First, engage contact - 3 - of Ground (GND) connection into securing opening on fuel tank - 4 - and then press in spacer bushing - 5 -.
3. Ensure connector of Ground (GND) connection - 1 - fits securely at metal ring - 2 - of fuel filler tube.

Fuel tank, emptying

A - Emptying a fuel tank more than 1 / 4 filled --> A - Emptying a fuel tank more than 1/4 filled .

B - Emptying a fuel tank less than 1 / 4 filled --> B - Emptying a fuel tank less than 1/4 filled .

Special tools, testers and auxiliary items required

Scheme 3

1. Fuel siphoning unit VAS 5190

Work procedure

Observe safety precautions --> Safety precautions .

Observe rules for cleanliness --> Rules for cleanliness .

1. Switch off ignition.
2. Release fuel tank flap.

Sedan

1. Fold luggage compartment floor upward.

Wagon

Scheme 4

1. Remove luggage compartment cargo floor - 1 - and spare wheel cover - 2 -.

All

Scheme 5

1. Release retaining clips - arrows - with a screwdriver - 2 - and remove cover - 1 -.

Scheme 6

1. Disconnect Ground (GND) strap at battery Ground (GND) terminal - arrow -.

Scheme 7

1. Remove cone piece - 2 - from Fuel Extraction Unit VAS 5190 shaft piece - 1 -.
2. Using insulating tape, apply a mark - arrow - on hose at length - a - = 1,365 mm from end of suction hose.

Scheme 8

1. Remove fuel filler cap from fuel filler tube.
2. Attach shaft piece - 1 - of Fuel Extraction Unit VAS 5190 to fuel filler tube of fuel tank.
3. Slide suction hose as far into fuel tank until mark applied earlier - arrow - stands on shaft piece.
4. Empty fuel tank as much as possible via fuel filler tube.

1. Carefully pull out suction hose.
2. Remove fuel delivery unit --> «Fuel delivery unit, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-delivery-unit-removing-and-installing) .
3. Extract residual fuel in right chamber of fuel tank through opening of fuel filler tube.
4. Push hose into left chamber of fuel tank and extract residual fuel.

Note. If using a siphoning device without shaft piece, proceed principally in the same manner. In this case, apply a mark - arrow - using insulating tape on hose at length - a - = 1300 mm from end of suction hose - 1 -. The suction hose is inserted correctly when the marking applied earlier stands opposite the lip of fuel filler tube. If the hose can only be inserted with difficulty, coat it thinly with engine oil. Never use lubricants containing silicon.

B - Emptying a fuel tank less than 1/4 filled

1. Remove fuel delivery unit --> «Fuel delivery unit, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-delivery-unit-removing-and-installing) .
2. Extract fuel in right chamber of fuel tank through opening of fuel filler tube.
3. Push hose into left chamber of fuel tank and extract residual fuel.

Fuel tank with attachments, removing and installing

Special tools, testers and auxiliary items required

Scheme 9

1. Engine/transmission jack V.A.G 1383 A

Removing

Observe safety precautions --> Safety precautions .

Observe rules for cleanliness --> Rules for cleanliness .

1. Switch off ignition.
2. Release fuel tank flap.
3. Fold rear seat right backrest forward, if necessary.

Sedan

1. Remove luggage compartment floor trim.

Wagon

1. Remove luggage compartment cargo floor - 1 - and spare wheel cover - 2 -.

All

1. Release retaining clips - arrows - with a screwdriver - 2 - and remove cover - 1 -.

1. Disconnect Ground (GND) strap at battery Ground (GND) terminal - arrow -.

Wagon

Scheme 10

1. On vehicles without air suspension, unclip right sealing flange cover retainers - arrow -.

Scheme 11

1. On vehicles with air suspension, remove spreader pins - arrows - and remove cover - 1 -.

All

Scheme 12

1. On vehicles with air suspension, remove bolts - arrows -.
2. Remove pressure tank - 2 - and set aside with line connected - 1 -.

Note. Do not stretch or kink line.

Sedan

Scheme 13

1. Release retaining tabs - arrows -.

Scheme 14

1. Fold open retaining tabs - 1 - and - 3 - toward rear.
2. Fold cover - 2 - toward front - arrow -.

All

Scheme 15

1. Remove cover - arrows -.

Scheme 16

1. Disconnect ventilation line - 1 -. Do this by pressing releasing ring - 2 - approx. 2 mm in direction - arrow A - and simultaneously pulling vent line off - arrow B -.

Scheme 17

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Remove cover for right locking flange - arrows -.

Scheme 18

1. Disconnect electrical harness connector - arrow - at locking flange.
2. Open fuel tank flap.
3. Clean area around fuel filler tube.

Scheme 19

1. Remove fuel filler cap - arrow - from fuel filler tube.
2. Close off opening of fuel filler tube with a clean piece of foam to prevent dirt from falling in.

Scheme 20

1. Remove right rear wheel.
2. Remove right rear wheel housing liner --> «66 - EXTERIOR EQUIPMENT»(/audi/a6/6-2004-2008/remont/door-locks-anti-theft-systems/#body-exterior) .
3. Pull vent lines - 1 - and - 2 - off from fuel filler tube by pressing release buttons.
4. Unfasten bolts - arrows - for fuel filler tube.

Scheme 21

1. Remove bolts - arrows - and remove cover for EVAP canister.
2. Secure EVAP canister by hand-tightening unfastened bolts.

Scheme 22

1. Disconnect vent line - 1 -. Do this by pressing releasing ring - 2 - approx. 2 mm in direction - arrow A - and simultaneously pulling vent line off - arrow B -.
2. Unclip vent line from bracket.

Scheme 23

1. Loosen clamping sleeves - 1 - and - 2 -.
2. Push clamping sleeves rearward to separate exhaust system.

Scheme 24

1. Remove rear cross member - arrows -.

Note. A second technician is required to remove rear portion of exhaust system.

1. Unhook exhaust system from retaining loops and remove rear portion of exhaust system.

Scheme 25

1. Remove left rear cover - 1 - on bottom of vehicle floor.

Scheme 26

1. Remove right rear cover - 1 - on bottom of vehicle floor.

Vehicles with all wheel drive

1. Remove driveshaft --> «39 FINAL DRIVE, REAR DIFFERENTIAL»(/audi/a6/6-2004-2008/remont/differentials-drive-axles/#rear-final-drive-01r) for REAR FINAL DRIVE 01R «39 - FINAL DRIVE, DIFFERENTIAL»(/audi/a6/6-2004-2008/remont/differentials-drive-axles/#rear-final-drive-0ar) for REAR FINAL DRIVE 0AR .

All

1. Remove rear axle --> «42 - REAR SUSPENSION»(/audi/a6/6-2004-2008/remont/axle-shafts/#suspension-wheels-steering) .

Scheme 27

1. Separate fuel line - 1 - and right vent line - 2 - from fuel tank, by pressing release buttons.
2. Place Engine/transmission jack V.A.G 1383 A under fuel tank for support.

Scheme 28

1. Remove bolts - 1 to 9 -.
2. Lower fuel tank with Engine/transmission jack V.A.G 1383 A , thereby guiding it by hand.

Installing

1. Tightening torques --> «Fuel tank with attachments, assembly overview»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .

Installation is in reverse order of removal, note the following

1. Make sure fuel and vent lines are properly clipped to fuel tank.

1. Check if Ground (GND) wiring on both connections show signs of oxidation. If necessary, remove.
2. Check installation position of Ground (GND) connection

1. The connector - 1 - must be securely attached to metal ring - 2 -.
2. The contact - 3 - must be attached into fuel tank - 4 - and be secured with spacer bushing - 5 -.

1. Position fuel tank with mounting straps and carrier plate to vehicle floor using Engine/transmission jack V.A.G 1383 A.
2. Make sure fuel tank is positioned so that the filler tube can be correctly guided into opening of the body.
3. Fasten mounting straps and carrier plate - 1 to 9 -.

1. Fasten fuel filler tube with Ground (GND) connection - arrows -.

1. Secure vent lines - 1 - and - 2 - to fuel filler tube.
2. Install rear axle --> «42 - REAR SUSPENSION»(/audi/a6/6-2004-2008/remont/axle-shafts/#suspension-wheels-steering) .

Vehicles with all wheel drive

1. Install driveshaft --> «39 FINAL DRIVE, REAR DIFFERENTIAL»(/audi/a6/6-2004-2008/remont/differentials-drive-axles/#rear-final-drive-01r) for REAR FINAL DRIVE 01R «39 - FINAL DRIVE, DIFFERENTIAL»(/audi/a6/6-2004-2008/remont/differentials-drive-axles/#rear-final-drive-0ar) for REAR FINAL DRIVE 0AR .

All

1. Install rear part of exhaust system --> «26 - EXHAUST SYSTEM, EMISSION CONTROLS»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-engine-mechanical-engine-codes-bkh) for 3.2 V6 4V ENGINE MECHANICAL, ENGINE CODE(S): BKH 26 - EXHAUST SYSTEM, EMISSION CONTROLS for 4.2 LITER V8 4V ENGINE MECHANICAL, ENGINE CODE(S): BAT, BNK «26 - EXHAUST SYSTEM, EMISSION CONTROLS»(ref-281367-S05556147682008031100000) for 4.2 LITER V8 4V ENGINE MECHANICAL, ENGINE CODE(S): BVJ «26 - EXHAUST SYSTEM, EMISSION CONTROLS»(ref-281368-S35333684742008031100000) for 5.2 LITER 10-CYL. 4V ENGINE MECHANICAL ENGINE CODE(S): BXA .
2. Install right rear wheel housing liner --> «66 - EXTERIOR EQUIPMENT»(/audi/a6/6-2004-2008/remont/door-locks-anti-theft-systems/#body-exterior) .
3. Install EVAP canister cover --> «Evaporative emissions (EVAP) canister, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__evaporative-emissions-evap-canister-removing-and)
4. Install rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .

1. Install pressure tank --> «43 - SELF LEVELING SUSPENSION»(/audi/a6/6-2004-2008/remont/axle-shafts/#suspension-wheels-steering) .
2. Connect battery. Observe safety precautions after connecting battery --> «27 - STARTER, GENERATOR, CRUISE CONTROL»(/audi/a6/6-2004-2008/remont/cruise-control-systems/#electrical-equipment) .

Scheme 29

1 - Fuel delivery unit

1. Fuel pump electrical, checking --> «Fuel pump electrical, checking»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system)
2. Removing and installing --> «Fuel delivery unit, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-delivery-unit-removing-and-installing)
3. Checking residual pressure --> «24 - FUEL INJECTION SYSTEM»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-fuel-injection-ignition-engine-codes-bkh) for 3.2 V6 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BKH «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281374-S05905131272008031100000) for 4.2 LITER V8 4V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BVJ 24 - MULTIPORT FUEL INJECTION (MFI) for 4.2 LITER V8 5V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BAT, BNK «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281372-S35275104102008031100000) for 5.2 LITER 10-CYL. 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BXA

2 - Fuel Level Sensor G

1. Resistance values, checking --> «Fuel Level Sensor G , checking»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-level-sensor-g-checking)
2. Removing and installing --> «Fuel Level Sensor G , removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-level-sensor-g-removing)

3 - Threaded ring

4 - Seal

1. Replace
2. Install dry

5 - Union nut

1. Use ring nut wrench T40068 for removal and installation
2. Replace
3. 120 Nm

6 - Fuel return line

1. From fuel filter
2. Do not kink
3. Mark before removing
4. To remove from locking flange, press release button on connecting piece

1. Note direction of arrow (fuel supply or return) on locking flange when installing
2. Clipped in on fuel tank

7 - Fuel supply line

1. To fuel filter
2. Do not kink
3. Mark before removing
4. To remove from locking flange, press release button on connecting piece

1. Note direction of arrow (fuel supply or return) on locking flange when installing
2. Clipped in on fuel tank

8 - Electrical harness connector

1. For Transfer Fuel Pump (FP) G6
2. For Fuel Level Sensor G and Fuel Level Sensor 2 G169

9 - Electrical harness connector

1. For Fuel Level Sensor 2 G169

10 - Fuel delivery line

1. From suction jet pump to fuel delivery unit
2. Clipped into fuel delivery unit
3. Secure to suction jet pipe with a total of 3 cable ties

11 - Union nut

1. Use ring nut wrench T40068 for removal and installation
2. Replace
3. 120 Nm

12 - Seal

1. Replace
2. Install dry

13 - Threaded ring

14 - Suction jet pump

1. Suction jet pump, checking --> «Suction jet pump»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system)
2. Removing and installing --> «Suction jet pump, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__suction-jet-pump-removing-and-installing)

15 - Fuel Level Sensor 2 G169

1. Resistance values, checking --> «Fuel Level Sensor 2 G169 , checking»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-level-sensor-2-g169)
2. Removing and installing --> «Fuel Level Sensor 2 G169 , removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-level-sensor-2-g169)

16 - Suction jet pipe

1. From fuel pump to suction jet pump
2. To disconnect, press release button on connection piece
3. Secure on fuel delivery line with a total of 3 cable ties

Scheme 30

Special tools, testers and auxiliary items required

1. Remote control V.A.G 1348/3A with adapter cable V.A.G 1348/3-2
2. Portable multimeter V.A.G 1526C
3. Connector test set V.A.G 1594C

Work procedure

1. Battery voltage min. 12.5 V.

Scheme 31

1. Fuse 1 of right fuse panel in center bracket of instrument panel - 2 - is OK.

Scheme 32

1. Vehicles with MPI engine: Fuel Pump (FP) Relay J17 in relay and fuse carrier, position - 2 - in left E-Box is OK.

Scheme 33

1. Vehicles with FSI engine: Fuel Pump (FP) Control Module J538 OK; checking --> «Fuel Pump (FP) Control Module J538 , checking - Vehicles with FSI engine»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .
2. Fuel filter OK.
3. Ignition switched off.

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Unbolt cover for right locking flange - arrows -.

1. Disconnect electrical harness connector - arrow - at locking flange.

Scheme 34

1. Connect Remote Control V.A.G 1348/3A with Adapter Cable V.A.G 1348/3-2 with an adapter cable from Connector Test Set V.A.G 1594C at terminal - 1 -.
2. Connect contact - 5 - to vehicle ground (GND) using a jumper cable from the connector test set V.A.G 1594C.
3. Connect alligator clip to battery "+".
4. Press the switch on the remote control.

1. Running noise of pump must be audible.

Note. Fuel Pump (FP) runs quietly. Avoid surrounding noises while testing the fuel pump.

Scheme 35

If no operating noise can be heard

1. Remove fuel delivery unit --> «Fuel delivery unit, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-delivery-unit-removing-and-installing) .
2. Check if the electrical wiring between the flange and fuel pump is connected and has continuity.

If no malfunction is detected in wires, Fuel Pump (FP) is faulty - replace fuel pump.

1. Install fuel delivery unit «Installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__installing) .

Scheme 36

Special tools, testers and auxiliary items required

1. Portable multimeter V.A.G 1526C
2. Connector test set V.A.G 1594C
3. Adapter cable V.A.G 1598/39
4. Test box V.A.G 1598/42

Work procedure

1. Battery voltage min. 12.5 V.
2. Fuse 1 of right fuse panel in center bracket of instrument panel - 2 - is OK.
3. Ignition switched off.

Check voltage supply for Fuel Pump (FP) (from Fuel Pump (FP) Control Module J538)

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Unbolt cover for right locking flange - arrows -.

Scheme 37

1. For voltage testing, connect the hand multimeter V.A.G 1526C with measuring probes and connector adapters from the connector test set V.A.G 1594C between clamp - 1 - and - 5 - , as shown in the illustration. The electrical connection remains connected.

Note. Connector sockets are numbered respectively on the rear side of the connector.

1. Start engine.

1. Specified value at start and in idle: 4 to 5 V.

1. Depress accelerator pedal completely and then release it (brief throttle burst).

1. Specified value: The voltage value must first rise slightly, then fall and then rise again to the value previously read.

If the reading does not result as described

1. Check voltage supply and activation of Fuel Pump (FP) Control Module J538.

Check voltage supply for Fuel Pump (FP) Control Module J538

1. Remove Fuel Pump (FP) Control Module J538 --> «Fuel Pump (FP) Control Module J538 , removing and installing - Vehicles with FSI engine»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-pump-fp-control-module-j538) .
2. Disconnect electrical harness connector - arrow - on Fuel Pump (FP) Control Module J538.

Scheme 38

1. Connect multimeter between terminal - 3 - and - 4 - of harness connector for voltage measurement.
2. Switch ignition on.

1. Specified value: approx. battery voltage.

If the specification is not obtained

1. Repair open circuit in wiring according to wiring diagram.

Scheme 39

Fuel Pump (FP) Control Module J538 activation, checking

1. Remove protective cap.
2. For voltage testing, connect the multimeter with measuring probes and connector adapters from the connector test set V.A.G 1594C between clamp - 4 - and - 5 - , as shown in the illustration. The electrical connection remains connected.

Note. Connector sockets are numbered respectively on the rear side of the connector.

1. Start engine.

1. Specified value at start and in idle: approx. 5.0 V.

1. Depress accelerator pedal completely and then release it (brief throttle burst).

1. Specified value: The voltage value must first rise slightly, then fall and then rise again to the value previously read.

Scheme 40

If the reading does not result as described

1. Switch off ignition.
2. Connect Test Box V.A.G 1598/42 to wiring harness with adapter cable V.A.G 1598/39-1 or V.A.G 1598/39-2 ; engine control module (ECM) is not connected. Clamp test box Ground (GND) clip to battery negative terminal --> «24 - FUEL INJECTION SYSTEM»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-fuel-injection-ignition-engine-codes-bkh) for 3.2 V6 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BKH «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281374-S05905131272008031100000) for 4.2 LITER V8 4V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BVJ 24 - MULTIPORT FUEL INJECTION (MFI) for 4.2 LITER V8 5V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BAT, BNK «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281372-S35275104102008031100000) for 5.2 LITER 10-CYL. 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BXA .

1. Check the following wire connection for open circuit and short circuit to Ground (GND) and B+

1. Repair wiring open circuit or short circuit according to wiring diagram.

If no malfunctions are detected

1. Replace the Fuel Pump (FP) Control Module J538.

Fuel Pump (FP) Control Module J538 , removing and installing - Vehicles with FSI engine

Removing

Observe safety precautions --> Safety precautions .

Observe rules for cleanliness --> Rules for cleanliness .

1. Switch off ignition.
2. Release the fuel tank flap.

Sedan

1. Fold the luggage compartment floor upward.

Wagon

1. Remove luggage compartment cargo floor - 1 - and spare wheel cover - 2 -.

All

1. Release the retaining clips - arrows - with a screwdriver - 2 - and remove the cover - 1 -.

1. Disconnect Ground (GND) strap at battery Ground (GND) terminal - arrow -.

1. Open the fuel tank flap.
2. Clean the area around the fuel filler tube.
3. Remove fuel filler cap - arrow - from fuel filler tube.
4. Close off the opening of the fuel filler tube with a clean piece of foam to prevent dirt from falling in.

1. Remove right rear wheel.
2. Remove rear right wheel housing liner --> «66 - EXTERIOR EQUIPMENT»(/audi/a6/6-2004-2008/remont/door-locks-anti-theft-systems/#body-exterior) .
3. Pull vent line - 2 - off from fuel filler tube by pressing the release buttons.

Note. Ignore - 1 -.

1. Unfasten the bolts - arrows - for fuel filler tube.

1. Remove right rear cover - 1 - on bottom of vehicle floor.

1. Loosen bolts - 1, 2, 3, 4, 8, 9 - a maximum of 8 turns.
2. Remove bolts - 5, 6, 7 -.

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Unbolt cover for right locking flange - arrows -.

1. Disconnect electrical harness connector - arrow - at locking flange.

Scheme 41

1. Mark the fuel supply line - 1 - and fuel return line - 2 -.

1. Pull both lines from locking flange, by pressing the release buttons.

Scheme 42

1. Remove the bolts - arrows -.
2. Remove Fuel Pump (FP) Control Module J538 with bracket.

Installing

1. Tightening torques --> «Fuel tank with attachments, assembly overview»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .

Installation is performed in the reverse order of removal, noting the following

1. Fasten mounting straps and carrier plate - 1 to 9 -.

1. Fasten the fuel filler tube with ground (GND) connection - arrows -.

1. Secure vent line - 2 - to fuel filler tube.

Note. Ignore - 1 -.

1. Install rear right wheel housing liner --> «66 - EXTERIOR EQUIPMENT»(/audi/a6/6-2004-2008/remont/door-locks-anti-theft-systems/#body-exterior) .
2. Install rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
3. Connect battery. Observe safety precautions after connecting battery --> «27 - STARTER, GENERATOR, CRUISE CONTROL»(/audi/a6/6-2004-2008/remont/cruise-control-systems/#electrical-equipment) .

Torque specifications

Fuel pump, vehicles with 6-cyl. and 8-cyl. engine, checking delivery rate

Special tools, testers and auxiliary items required

Scheme 43

1. Pressure gauge K-Jetronic V.A.G 1318
2. Pressure gauge adapter V.A.G 1318/10-12

Scheme 44

1. Remote Control V.A.G 1348/3A with adapter cable V.A.G 1348/3-3
2. Measuring container, fuel-resistant

Work procedure

1. Battery voltage min. 12.5 V.
2. Fuse 1 of right fuse panel in center bracket of instrument panel - 2 - is OK.
3. Ignition switched off.

1. Vehicles with MPI engine: Fuel Pump (FP) Relay J17 in relay and fuse carrier, position - 2 - in left E-Box is OK.

1. Vehicles with FSI engine: Fuel Pump (FP) Control Module J538 OK; checking --> «Fuel Pump (FP) Control Module J538 , checking - Vehicles with FSI engine»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .
2. Fuel filter OK.
3. Fuel tank at least 1 / 4 filled.
4. Ignition switched off.

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Remove cover for right locking flange - arrows -.

1. Disconnect electrical harness connector - arrow - at locking flange.

Scheme 45

1. Connect Remote Control V.A.G 1348/3A with adapter cable V.A.G 1348/3-3 with an adapter cable from Connector Test Set V.A.G 1594C at terminal - 5 -.
2. Cover 2nd connector terminal of adapter cable V.A.G 1348/3-3 with insulating tape to prevent short circuit - arrow -.
3. Route Remote Control V.A.G 1348/3A switch forward in engine compartment.
4. Connect alligator clip to Ground (GND) point in engine compartment.

1. Connect contact - 1 - to battery "+" using a self-made adapter cable. For safety reasons, install a fuse - A - (10 A) in wiring.
2. Remove fuel filler cap from fuel filler tube.

Scheme 46

1. Pull rear engine cover off - arrows -.

Vehicles with 8-cyl. engine

Scheme 47

1. Pull resonator - 1 - upward - arrow - and unclip it.

All

Scheme 48

1. Disconnect fuel line - arrow -.

Note. Shown in illustration on a vehicle with 6-cyl. engine.

Scheme 49

1. Connect Fuel Inj. Pressure Gauge-CIS V.A.G 1318 with Adapter V.A.G 1318/11 and V.A.G 1318/12 in fuel line.
2. Push an assisting hose - arrow - onto it and hold it into a measuring container.
3. Open shut-off valve of pressure gauge.

1. The lever points in direction of flow.

1. Generate pressure in fuel system by pressing switch of remote control and slowly closing shut-off valve of pressure gauge.

1. Specified value: 4 bar positive pressure.

1. From this point on do not move position of shut-off tap.
2. Empty measuring container.
3. Press switch on remote control for 15 seconds.

Scheme 50

1. Compare quantity of fuel delivered with minimum delivery rate in diagram (cm 3 /15s).

Note. Voltage at fuel pump with engine stopped and pump running is approx. 2 volts less than battery voltage.

If minimum delivery quantity is not obtained, the following malfunctions may be present

1. Fuel lines pinched.
2. Fuel filter clogged.
3. Fuel pump faulty.

Assembly is in reverse order of removal, note the following

1. Attach fuel line to engine --> «24 - FUEL INJECTION SYSTEM»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-fuel-injection-ignition-engine-codes-bkh) for 3.2 V6 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BKH «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281374-S05905131272008031100000) for 4.2 LITER V8 4V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BVJ 24 - MULTIPORT FUEL INJECTION (MFI) for 4.2 LITER V8 5V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BAT, BNK «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281372-S35275104102008031100000) for 5.2 LITER 10-CYL. 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BXA .

Fuel pump delivery rate, vehicles with 8-cyl. FSI engine, checking

Special tools, testers and auxiliary items required

1. Pressure gauge K-Jetronic V.A.G 1318
2. Pressure gauge adapter V.A.G 1318/10-12

1. Remote Control V.A.G 1348/3A with adapter cable V.A.G 1348/3-3
2. Measuring container, fuel-resistant

Work procedure

1. Battery voltage min. 12.5 V.

1. Fuse 1 of right fuse panel in center bracket of instrument panel - 2 - is OK.

1. Fuel Pump (FP) Control Module J538 OK; checking --> «Fuel Pump (FP) Control Module J538 , checking - Vehicles with FSI engine»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .
2. Fuel filter OK.
3. Fuel tank at least 1 / 4 filled.
4. Ignition switched off.

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Remove cover for right locking flange - arrows -.

1. Disconnect electrical harness connector - arrow - at locking flange.

Scheme 51

1. Connect Remote Control V.A.G 1348/3A with adapter cable V.A.G 1348/3-3 with an adapter cable from Connector Test Set V.A.G 1594C at terminal - 1 -.
2. Cover 2nd connector terminal of adapter cable V.A.G 1348/3-3 with insulating tape to prevent short circuit - arrow -.
3. Route Remote Control V.A.G 1348/3A switch forward in engine compartment.
4. Release retaining clip and open cover - A - over positive terminal pick-off.

1. Connect alligator clip to positive terminal pick-off (+).
2. Connect contact - 5 - to vehicle Ground (GND) using a jumper cable from connector test set V.A.G 1594C.
3. Remove fuel filler cap from fuel filler tube.

Scheme 52

1. Pull rear engine cover - arrows - off.

Scheme 53

1. Disconnect fuel line - arrow -.

1. Connect Fuel Inj. Pressure Gauge-CIS V.A.G 1318 with Adapter V.A.G 1318/11 and V.A.G 1318/12 in fuel line.
2. Push an assisting hose - arrow - and hold it into a measuring container.
3. Open shut-off valve of pressure gauge.

1. The lever points in direction of flow.

1. Generate pressure in fuel system by pressing the remote control switch and slowly closing shut-off valve of pressure gauge.

1. Specified value: 4 bar positive pressure.

1. From this point on do not move position of shut-off tap.
2. Empty measuring container.
3. Press switch on remote control for 15 seconds.

Scheme 54

1. Compare quantity of fuel delivered with minimum delivery rate in diagram (cm 3 /15s).

Note. Voltage at fuel pump with engine stopped and pump running is approx. 2 volts less than battery voltage.

If minimum delivery quantity is not obtained, the following malfunctions may be present

1. Fuel lines pinched.
2. Fuel filter clogged.
3. Fuel pump faulty.

Assembly is in reverse order of removal, note the following

1. Attach fuel line to engine --> «24 - FUEL INJECTION SYSTEM»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-fuel-injection-ignition-engine-codes-bkh) for 3.2 V6 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BKH «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281374-S05905131272008031100000) for 4.2 LITER V8 4V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BVJ 24 - MULTIPORT FUEL INJECTION (MFI) for 4.2 LITER V8 5V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BAT, BNK «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281372-S35275104102008031100000) for 5.2 LITER 10-CYL. 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BXA .

Fuel pump (vehicles with 10-cyl. engine (Audi S6)), checking delivery rate

Special tools, testers and auxiliary items required

1. Pressure gauge K-Jetronic V.A.G 1318
2. Pressure gauge adapter V.A.G 1318/10-12

1. Remote Control V.A.G 1348/3A with adapter cable V.A.G 1348/3-3
2. Measuring container, fuel-resistant

Work procedure

1. Battery voltage min. 12.5 V.

1. Fuse 1 of right fuse panel in center bracket of instrument panel - 2 - is OK.

1. Fuel Pump (FP) Control Module J538 OK; checking --> «Fuel Pump (FP) Control Module J538 , checking - Vehicles with FSI engine»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .
2. Fuel filter OK.
3. Fuel tank at least 1 / 4 filled.
4. Ignition switched off.

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Remove cover for right locking flange - arrows -.

1. Disconnect electrical harness connector - arrow - at locking flange.

1. Connect Remote Control V.A.G 1348/3A with adapter cable V.A.G 1348/3-3 with an adapter cable from Connector Test Set V.A.G 1594C at terminal - 1 -.
2. Cover 2nd connector terminal of adapter cable V.A.G 1348/3-3 with insulating tape to prevent short circuit - arrow -.
3. Route Remote Control V.A.G 1348/3A switch forward in engine compartment.
4. Release retaining clip and open cover - A - over positive terminal pick-off.

1. Connect alligator clip to positive terminal pick-off (+).
2. Connect contact - 5 - to vehicle Ground (GND) using a jumper cable from connector test set V.A.G 1594C.
3. Remove fuel filler cap from fuel filler tube.

Scheme 55

1. Remove rear engine cover - 2 - - arrows -.

Note. Ignore - 1 -.

Scheme 56

1. Disconnect fuel line - arrow - on fuel rail.

Scheme 57

1. Connect Fuel Inj. Pressure Gauge-CIS V.A.G 1318 with Adapter V.A.G 1318/11 and V.A.G 1318/12 in fuel line.
2. Push an assisting hose - arrow - onto it and hold it into a measuring container.
3. Open shut-off valve of pressure gauge.

1. The lever points in direction of flow.

1. Generate pressure in fuel system by pressing switch of remote control and slowly closing shut-off valve of pressure gauge.

1. Specified value: 4 bar positive pressure.

1. From this point on do not move position of shut-off tap.
2. Empty measuring container.
3. Press switch on remote control for 15 seconds.

1. Compare quantity of fuel delivered with minimum delivery rate in diagram (cm 3 /15s).

Note. Voltage at fuel pump with engine stopped and pump running is approx. 2 volts less than battery voltage.

If minimum delivery quantity is not obtained, the following malfunctions may be present

1. Fuel lines pinched.
2. Fuel filter clogged.
3. Fuel pump faulty.

Assembly is in reverse order of removal, note the following

1. Attach fuel line to fuel rail --> «24 - FUEL INJECTION SYSTEM»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-fuel-injection-ignition-engine-codes-bkh) for 3.2 V6 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BKH «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281374-S05905131272008031100000) for 4.2 LITER V8 4V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BVJ 24 - MULTIPORT FUEL INJECTION (MFI) for 4.2 LITER V8 5V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BAT, BNK «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281372-S35275104102008031100000) for 5.2 LITER 10-CYL. 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BXA .

Fuel delivery unit, removing and installing

Special tools, testers and auxiliary items required

Scheme 58

1. Ring nut wrench T40068

Removing

Observe safety precautions --> Safety precautions .

Observe rules for cleanliness --> Rules for cleanliness .

1. If necessary, move front seats completely forward.

1. Switch off ignition.

Sedan

1. Fold luggage compartment floor upward.

Wagon

1. Remove luggage compartment cargo floor - 1 - and spare wheel cover - 2 -.

All

1. Release retaining clips - arrows - with a screwdriver - 2 - and remove cover - 1 -.

1. Disconnect Ground (GND) strap at battery Ground (GND) terminal - arrow -.

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Remove cover for right locking flange - arrows -.

1. Disconnect electrical harness connector - arrow - at right locking flange.

1. Mark fuel supply line - 1 - and fuel return line - 2 -.

1. Pull both lines from locking flange, by pressing release buttons.

Scheme 59

1. Remove union nut using Ring nut spanner T40068.

Note. When union nut is loosened, plastic catch on threaded ring breaks off - ignore.

Scheme 60

1. Pull right locking flange of fuel delivery unit out of opening in fuel tank and set aside with lines still connected.
2. Through opening in fuel tank, disconnect electrical harness connector - 2 - for Fuel Level Sensor 2 G169.
3. Disconnect suction jet pipe - 1 - to suction jet pump by pressing release button.
4. Disengage fuel delivery line - 3 -.

1. Remove fuel delivery unit.

Note. When removing fuel delivery unit, be sure not to bend floater arm of Fuel Level Sensor G. Be aware that fuel is still in the fuel delivery unit.

Installing

1. Tightening torque --> «Fuel delivery unit and fuel level sensor, assembly overview»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .

Installation is in reverse order of removal, noting the following

Note. Always replace seal and union nut. When inserting fuel delivery unit, be sure not to bend floater arm of fuel level sensor G. Ensure fuel hoses are seated securely.

1. Insert fuel delivery unit into fuel tank with locking flange set aside.
2. Attach fuel delivery line - 3 -.
3. Push suction jet pipe - 1 - onto suction jet pump until it engages audibly.
4. Connect electrical connector - 2 - for Fuel Level Sensor 2 G169.

Make sure fuel hoses are routed correctly

Scheme 61

1. The fuel supply line - 1 - must be routed between the guide tube - 4 - and supports - 2 - for fuel return line. Also, it must be routed around outside of the guide tube - 3 -.

1. Insert guide tubes - 3 - and - 4 - of the locking flange into guide holes - arrows - of fuel delivery unit.

Note. To improve clarity, the fuel delivery unit is shown without the fuel tank.

1. Install new locking flange seal dry.
2. Press locking flange down against spring pressure and bring it into installation position.

Scheme 62

1. Tab - 2 - on locking flange must lie between tabs - 1 - and - 3 - on threaded ring.

Scheme 63

Note. To install, position union nut so that the double ridge - 1 - of the ribs aligns with tab - 2 - of the locking flange. This will make it easier for union nut to engage beginning of thread - 3 -.

1. Tighten union nut for right locking flange.

1. Install fuel supply line - 1 - and fuel return line - 2 - according to the marking.
2. Connect electrical harness connector.
3. Install rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
4. Connect battery. Observe safety precautions after connecting battery --> «27 - STARTER, GENERATOR, CRUISE CONTROL»(/audi/a6/6-2004-2008/remont/cruise-control-systems/#electrical-equipment) .

Fuel Level Sensor G , checking

Special tools, testers and auxiliary items required

Scheme 64

1. Portable multimeter V.A.G 1526C

Scheme 65

1. Connector test set V.A.G 1594C

Work procedure

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .

1. Remove cover for right locking flange - arrows -.

1. Disconnect electrical harness connector - arrow - at locking flange.

Scheme 66

1. Connect multimeter between terminal - 2 - and - 3 - for resistance measurement.

Fuel Level Sensor G installed

1. Sensor at lower stop: approx. 760 to 1003 ohms.
2. Sensor at upper stop: approx. 70 to 105 ohms.

Note. If measured value is 0 ohms there is a short circuit. If measured value is infinity ohms there is and open circuit in the wiring. To check resistance values "tank full" or "tank empty" , the fuel delivery unit must be removed --> Fuel delivery unit, removing and installing and the floater of the sensor must be placed in upper or lower end position. With fuel gauge sensor removed, the following values are obtained because of the greater deflection of the floater arm

Fuel Level Sensor G removed

1. Sensor at lower stop: approx. 1004 ohms.
2. Sensor at upper stop: approx. 50 ohms.

Assembly is in reverse order of removal, note the following

1. Install rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .

Fuel Level Sensor G , removing and installing

Removing

Note. All cable ties which are opened or cut open when removing, must be replaced in the same position when installing.

Observe safety precautions --> Safety precautions .

Observe rules for cleanliness --> Rules for cleanliness .

Scheme 67

1. Remove fuel delivery unit --> «Fuel delivery unit, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-delivery-unit-removing-and-installing) .
2. Cut cable ties - 2 - and separate electrical connection - 1 -.
3. Release retaining tabs - arrows - with a screwdriver and pull fuel gauge sensor G upward and out.

Installing

Installation is in reverse order of removal, note the following

Note. During installation, the cable ties must be re-installed at the same location.

1. Insert fuel gauge sensor G in guides on the fuel delivery unit and push down until it engages.
2. Connect electrical connection and check that it is securely engaged.
3. Install fuel delivery unit «Installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__installing) , observing notes for connecting battery.

Fuel Level Sensor 2 G169 , checking

Special tools, testers and auxiliary items required

1. Portable multimeter V.A.G 1526C

1. Connector test set V.A.G 1594C

Work procedure

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .

1. Remove cover for right locking flange - arrows -.

1. Disconnect electrical harness connector - arrow - at locking flange.

1. Connect multimeter between terminal - 3 - and - 4 - for resistance measurement.

Fuel Level Sensor 2 G169 installed

1. Sensor at lower stop: approx. 790 to 975 ohms.
2. Sensor at upper stop: approx. 50 to 86 ohms.

Note. If measured value is 0 ohms there is a short circuit. If measured value is infinity ohms there is and open circuit in the wiring. To check resistance values "tank full" or "tank empty" , the Fuel Level Sensor 2 G169 must be removed --> Fuel Level Sensor 2 G169 , removing and installing and the sensor floater must be placed in upper or lower end position. With fuel gauge sensor removed, the following values are obtained because of the greater deflection of the floater arm

Fuel Level Sensor 2 G169 removed

1. Sensor at lower stop: approx. 1004 ohms.
2. Sensor at upper stop: approx. 50 ohms.

Assembly is in reverse order of removal, note the following

1. Install rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .

Fuel Level Sensor 2 G169 , removing and installing

Special tools, testers and auxiliary items required

1. Ring nut wrench T40068

Observe safety precautions --> Safety precautions .

Observe rules for cleanliness --> Rules for cleanliness .

1. Switch off ignition.

Sedan

1. Fold luggage compartment floor upward.

Wagon

1. Remove luggage compartment cargo floor - 1 - and spare wheel cover - 2 -.

All

1. Release retaining clips - arrows - with a screwdriver - 2 - and remove cover - 1 -.

1. Disconnect Ground (GND) strap at battery Ground (GND) terminal - arrow -.

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Remove cover for left locking flange - arrows -.

1. Remove left union nut using Ring nut spanner T40068.

Note. When union nut is loosened, plastic catch on threaded ring breaks off - ignore.

Scheme 68

1. Carefully pull Fuel Level Sensor 2 G169 - 1 - and suction jet pump - 2 - partially out of fuel tank opening.

Note. When removing, be sure not to bend floater arm of Fuel Level Sensor 2 G169.

Scheme 69

1. Unclip suction jet pump from locking flange.
2. Separate electrical connector - 1 -.
3. Release retaining tabs - arrows - with a screwdriver and remove Fuel Level Sensor 2 G169.

1. Tightening torque --> «Fuel delivery unit and fuel level sensor, assembly overview»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .

Installation is in reverse order of removal, noting following

Note. Always replace seal and union nut.

1. Insert Fuel Level Sensor 2 G169 in guides on locking flange and press in until it engages.
2. Connect electrical connection and check that it is securely engaged.
3. Clip suction jet pump to locking flange so that it is audibly engaged.
4. Check whether fuel delivery line is connected to suction jet pipe with at least 3 cable ties.

Note. When inserting, be sure not to bend floater arm of Fuel Level Sensor 2 G169.

1. Carefully insert Fuel Level Sensor 2 G169 in fuel tank opening.
2. Install new locking flange seal dry.
3. Press locking flange down against spring pressure and bring it into installation position.

Scheme 70

1. Tab - 2 - on locking flange must lie between tabs - 1 - and - 3 - on threaded ring.

Note. To install, position union nut so that the double ridge - 1 - of the ribs aligns with tab - 2 - of the locking flange. This will make it easier for union nut to engage beginning of thread - 3 -.

1. Tighten union nut for left locking flange.

1. Install rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Connect battery. Observe safety precautions after connecting battery --> «27 - STARTER, GENERATOR, CRUISE CONTROL»(/audi/a6/6-2004-2008/remont/cruise-control-systems/#electrical-equipment) .

Scheme 71

The fuel tank in a vehicle with all-wheel drive is divided into a left and right chamber. To move the volume of fuel from the left fuel tank chamber - 3 - to right baffle housing of fuel delivery unit - 2 - , a suction jet pump - 1 - is utilized.

Function of suction jet pump

Function of the suction jet pump is based on a simple physical principle: A suction jet from the electrical fuel pump is compressed by a nozzle in the suction jet pump and is thereby accelerated. This acceleration causes the surrounding fuel to be drawn in and be forced to the baffle housing of the fuel delivery unit.

Malfunctions of faulty suction jet pump

If suction jet pump does not function, up to 20 liters of fuel (up to approx. 1 / 4 tank) remain in left chamber of fuel tank, because it can not be extracted by fuel delivery unit.

If vehicle stops running, although fuel tank is approx. 1 / 4 filled, proceed as follows

1. Check fuel pump --> «Fuel pump electrical, checking»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .

If fuel pump is OK, but no fuel is supplied

1. Fill fuel tank with approx. 5 liters of fuel.
2. Start engine.

If engine starts now

1. Replace suction jet pump --> «Suction jet pump, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__suction-jet-pump-removing-and-installing) .

Suction jet pump, removing and installing

Special tools, testers and auxiliary items required

1. Ring nut wrench T40068

Removing

Observe safety precautions --> Safety precautions .

Observe rules for cleanliness --> Rules for cleanliness .

1. If necessary, move front seats completely forward.

1. Switch off ignition.

Sedan

1. Fold luggage compartment floor upward.

Wagon

1. Remove luggage compartment cargo floor - 1 - and spare wheel cover - 2 -.

All

1. Release retaining clips - arrows - with a screwdriver - 2 - and remove cover - 1 -.

1. Disconnect Ground (GND) strap at battery Ground (GND) terminal - arrow -.

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Remove cover for right locking flange - arrows -.

1. Disconnect electrical harness connector - arrow - at locking flange.

1. Mark fuel supply line - 1 - and fuel return line - 2 -.

1. Pull both lines from locking flange, by pressing release buttons.

1. Remove right union nut using Ring nut spanner T40068.

Note. When union nut is loosened, plastic catch on threaded ring breaks off - ignore.

1. Pull right locking flange of fuel delivery unit out of opening in fuel tank and set aside with lines still connected.
2. Through opening in the fuel tank, disconnect electrical harness connector - 2 - for Fuel Level Sensor 2 G169.
3. Disconnect suction jet pipe - 1 - to suction jet pump by pressing release button.
4. Disengage fuel delivery line - 3 -.

1. Remove cover for left locking flange - arrows -.

1. Remove left union nut using Ring nut spanner T40068.

Note. When union nut is loosened, plastic catch on threaded ring breaks off - ignore.

1. Carefully pull Fuel Level Sensor 2 G169 - 1 - with suction jet pump - 2 - toward left and out of fuel tank opening.

Note. When removing, be sure not to bend floater arm of Fuel Level Sensor 2 G169.

Installing

1. Tightening torque --> «Fuel delivery unit and fuel level sensor, assembly overview»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .

Installation is in reverse order of removal, note the following

Note. Always replace seals and union nuts.

1. Clip suction jet pump to locking flange so that it is audibly engaged.
2. Check whether fuel delivery line is connected to suction jet pipe with at least 3 cable ties.

Note. When inserting, be sure not to bend floater arm of Fuel Level Sensor 2 G169.

1. Push suction jet pump with lines at left side of vehicle into fuel tank opening.

1. Reach into fuel tank opening on right side of vehicle and pull suction jet pump with lines into installed position.
2. Attach fuel delivery line - 3 -.
3. Push suction jet pipe - 1 - onto suction jet pump until it engages audibly.
4. Connect electrical connector - 2 - for Fuel Level Sensor 2 G169.

Make sure fuel hoses are routed correctly

1. The fuel supply line - 1 - must be routed between guide tube - 4 - and supports - 2 - for fuel return line. Also, it must be routed around outside of guide tube - 3 -.

1. Insert guide tubes - 3 - and - 4 - of locking flange into guide holes - arrows - of fuel delivery unit.

Note. To improve clarity, the fuel delivery unit is shown without the fuel tank.

1. Install new locking flange seal dry.
2. Press locking flange down against spring pressure and bring it into installation position.

1. Tab - 2 - on locking flange must lie between tabs - 1 - and - 3 - on threaded ring.

Note. To install, position union nut so that the double ridge - 1 - of the ribs aligns with tab - 2 - of the locking flange. This will make it easier for union nut to engage beginning of thread - 3 -.

1. Tighten union nut for right locking flange.

1. Install fuel supply line - 1 - and fuel return line - 2 - according to the marking.
2. Connect electrical harness connector.

1. Install new locking flange seal dry.
2. Press locking flange down against spring pressure and bring it into installation position.

1. Tab - 2 - on locking flange must lie between tabs - 1 - and - 3 - on threaded ring.

Note. To install, position union nut so that the double ridge - 1 - of the ribs aligns with tab - 2 - of the locking flange. This will make it easier for union nut to engage beginning of thread - 3 -.

1. Tighten union nut for left locking flange.

1. Install rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Connect battery. Observe safety precautions after connecting battery --> «27 - STARTER, GENERATOR, CRUISE CONTROL»(/audi/a6/6-2004-2008/remont/cruise-control-systems/#electrical-equipment) .

Scheme 72

1 - Bolt

1. 1.2 Nm

2 - Fuel tank with bracket

1. For fuel filter

3 - Fuel filter with pressure regulator

1. FSI engine: 6 bar pressure
2. MPI engine: 4 bar pressure
3. Direction of flow is marked with arrows
4. Do not interchange connections

1. Removing and installing --> «Fuel filter, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__fuel-filter-removing-and-installing)
2. Installed location «Installed location»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__installed-location)

4 - Fuel line

1. To engine
2. To disconnect, press release button on connection piece

5 - Fuel return line

1. To fuel tank
2. To disconnect, press release button on connection piece

6 - Fuel supply line

1. From fuel tank
2. To disconnect, press release button on connection piece

Fuel filter, removing and installing

Special tools, testers and auxiliary items required

1. Drip tray

Removing

Observe safety precautions --> Safety precautions .

Observe rules for cleanliness --> Rules for cleanliness .

1. Remove right rear cover - 1 - next to fuel tank.

Scheme 73

1. Place drip tray under fuel filter.

1. Disconnect fuel lines - 1 - , - 2 - and - 4 - by pressing release buttons.
2. Remove bolts - 3 -.
3. Remove fuel filter.

Note. Shown in illustration on a vehicle with front wheel drive.

Installing

Installation is in reverse order of removal, note the following

Installed location

1. The direction of flow is marked on filter housing with arrows.

Scheme 74

1. Distance - a - = 10 to 14 mm between fuel return line at fuel filter and fuel tank.

Fuel system, bleeding

To prevent damage to catalytic converter the fuel system must be bled after repair work on fuel lines or on fuel filter.

Bleed fuel supply system -->

1. «24 - FUEL INJECTION SYSTEM»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-fuel-injection-ignition-engine-codes-bkh) for 3.2 V6 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BKH
2. «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281374-S05905131272008031100000) for 4.2 LITER V8 4V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BVJ
3. 24 - MULTIPORT FUEL INJECTION (MFI) for 4.2 LITER V8 5V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BAT, BNK
4. «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281372-S35275104102008031100000) for 5.2 LITER 10-CYL. 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BXA

Scheme 75

1 - Bolt

1. 19 Nm

2 - Cover

1. for EVAP canister

3 - Sealing piece

4 - Vent line

1. From fuel tank filler tube
2. To remove, press release ring on EVAP canister

5 - Vent line

1. To Evaporative Emission (EVAP) Canister Purge Regulator Valve N80
2. To remove, press release ring on EVAP canister
3. Clipped in on fuel tank

6 - Air filter housing

1. For Leak detection pump (LDP) V144
2. No maintenance schedule

7 - Nut

1. 4 Nm

8 - Vacuum line

1. Engine/Leak Detection Pump (LDP) V144

9 - Cable tie

1. To fasten vacuum line to bracket for leak detection pump

10 - Leak detection pump (LDP) V144

1. Component location: In left rear wheel housing behind wheel housing liner
2. Checking: Vehicles with 8-cyl. MPI engine --> «Leak Detection Pump (LDP) V144 (vehicles with 8-cyl. MPI engine), checking»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) , vehicles with FSI engine --> «Leak Detection Pump (LDP) V144 (vehicles with FSI engine), checking»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system)
3. Removing and installing --> «Leak Detection Pump (LDP) V144 , removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__leak-detection-pump-ldp-v144)

11 - Electrical harness connector

1. Black

12 - Connecting hose

1. Leak diagnosis pump/EVAP filter
2. Pressure side

13 - EVAP filter

14 - Connecting hose

1. Leak diagnosis pump/air filter

15 - Connecting pipe

1. EVAP filter/EVAP canister

16 - EVAP canister

1. Component location: Bottom of spare wheel well
2. Removing and installing --> «Evaporative emissions (EVAP) canister, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__evaporative-emissions-evap-canister-removing-and)

Evaporative emissions (EVAP) canister, removing and installing

Note. Checking for leaks --> Diagnostic leak test, performing .

Removing

1. Remove bolts - arrows - and remove cover for EVAP canister.
2. Secure EVAP canister by hand-tightening unfastened bolts.
3. Remove sealing pieces above vent lines.

Scheme 76

1. Separate hose connection - 1 - at vent line.
2. Pull off vent lines - 2 - and - 3 -. Do this by pressing releasing rings - 4 - approx. 2 mm in direction - arrows A - and simultaneously pulling vent line off - arrows B -.
3. Unfasten and remove EVAP canister.

Installing

1. Tightening torque --> «EVAP canister system/Leak detection system, assembly overview»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .

Installation is in reverse order of removal, note the following

Note. Secure all hose connections using hose clamps appropriate for the model type .

Hose routing, EVAP/leak detection system

Note. The diagram shows the hose routing on a 6-cyl. engine for example.

Scheme 77

1 - To Intake Air Switch-over valve N335

2 - Vacuum pump

1. For brake booster

3 - To brake booster

4 - Throttle valve control module J338

5 - Evaporative Emission (EVAP) Canister Purge Solenoid Valve N80

1. Component location: Right front in engine compartment

6 - Vent line

1. From EVAP canister to Evaporative Emission (EVAP) Canister Purge Regulator Valve N80
2. Installed location: At right beneath vehicle floor
3. Secured to fuel tank in fuel tank area

7 - Vent line

1. To fuel tank filler tube

8 - EVAP canister

1. Component location: Bottom of spare wheel well
2. Removing and installing --> «Evaporative emissions (EVAP) canister, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__evaporative-emissions-evap-canister-removing-and)

9 - Connecting hose

1. Pressure side

10 - EVAP filter

11 - Air filter housing

1. For Leak detection pump (LDP) V144

12 - Leak detection pump (LDP) V144

1. Component location: In left rear wheel housing behind wheel housing liner
2. Checking --> «Leak Detection Pump (LDP) V144 (vehicles with FSI engine), checking»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system)
3. Removing and installing --> «Leak Detection Pump (LDP) V144 , removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__leak-detection-pump-ldp-v144)

13 - Vacuum line

1. Engine/Leak Detection Pump (LDP) V144

14 - Separating point

1. Component location «Separation point location»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system)

15 - Intake manifold

16 - Non-return valve

1. Installed location: - Arrow - points in direction of flow

Scheme 78

The separating point - arrow - is located at lower left of engine compartment.

1. To disconnect, press release button on connection piece.

Leak detection system

Function

The leak detection system recognizes leaks in the complete fuel system, including the fuel tank, EVAP canister and Evaporative Emission (EVAP) Canister Purge Regulator Valve N80.

On the mechanical side, the leak detection system consists mainly of a vacuum-driven diaphragm pump, that is equipped with a reed contact on the actuation rod of the pump diaphragm. The pump is supplied with vacuum by the mechanical vacuum pump.

1. When leak detection is activated, the diaphragm pump pumps fuel system up to 20 to 30 mbar. The pump diaphragm is then moved out so that the reed contact at the operating rod remains in the "open" position.
2. During leak diagnosis, the reed contact is monitored to check if it remains open within 15 seconds. This indicates system is sealed.
3. If pressure falls (indicating a leak), the diaphragm moves back and reed contact closes.
4. If reed contact closes within 15 seconds of leak detection time, a further test is performed: In this case the diaphragm pump pumps 4 times again. The engine control module (ECM) measures the time for each of the 4 pumps until reed contact is closed again. From that, the control module can recognize a "small leak" (smaller than 1 mm in diameter) or a "large leak".

The leak detection is activated automatically, shortly after each cold start (under 35° C) and a drive faster than 10 km/h. In case a fault is detected, a DTC will be stored to memory. The Malfunction Indicator Lamp (MIL) in instrument cluster lights up if the malfunction is recognized for 2 subsequent starts. Leak diagnosis can also be activated using Vehicle Diagnosis, Testing and Information System VAS 5051 --> Diagnostic leak test, performing .

Automatic leak detection system

With engine running, the engine control module may perform a leak diagnosis at specific intervals.

It can be determined if an automatic leak diagnosis was recently performed by using Vehicle Diagnosis, Testing and Information System VAS 5051 in measured value block 071 --> Diagnostic leak test, performing .

Diagnostic leak test, performing

Special tools, testers and auxiliary items required

Scheme 79

1. Vehicle diagnostic, testing, and information system VAS 5051 (VAS 5051 B version shown as example only)

Note. Secure all hose connections using hose clamps appropriate for the model type . Replace seals and gaskets when performing repair work.

Work procedure

1. Parking brake engaged.
2. Selector lever in position P or N.
3. Engine running at idle speed or with brakes actuated and accelerator fully depressed (elevated engine RPM).
4. Electrical consumers switched off (Radiator fan must not run during test).

1. Air conditioning system switched off.

Scheme 80

1. Vehicle Diagnosis, Testing and Information System VAS 5051 connected.
2. No faults in DTC memory.
3. Intake air temperature less than 90° C --> Display group 004, display field 4.
4. Coolant temperature less than 95° C --> Display group 004, display field 3.

Observe safety precautions --> Safety precautions .

Observe rules for cleanliness --> Rules for cleanliness .

Scheme 81

Display on VAS 5051

1. Tap "On Board Diagnostic" in selection - 1 - and activate by tapping --> button.

Scheme 82

Display on VAS 5051

1. Tap "01 - Engine Electronics" vehicle system in selection - 1 - and activate by tapping --> button.

Scheme 83

Display on VAS 5051

1. Tap "006 - Basic Setting" function in selection - 1 - and activate by pressing --> button.

Scheme 84

Display on VAS 5051

1. In button field - 1 - , press buttons 7 1 for "display group 071" and confirm entry by pressing Q button.

Scheme 85

Display on VAS 5051

1. Check reading in display field - 1 -.

1. Specified value: "Reed closed".

Note. If "Reed closed" is displayed, continue test. If the reading on the display shows "Reed open" : Briefly open the cap of the fuel tank to relieve pressure - thereby the reed contact will close again.

Scheme 86

1. Activate basic setting by pressing Activate button - A -.

Display on VAS 5051

1. Check reading in display field - 4 -.

1. Specified value: "Test ON".

System test takes several minutes.

1. Check reading in display field - 4 -.

1. Specified value: "Syst.O.K.".

System is sealed, test is ended.

1. End function "006 - Basic setting" by pressing <-- button.

Fault indication

If a malfunction was recognized during the system test, the malfunction is indicated afterward.

On VAS 5051 display in display field - 4

1. In case of malfunction: Syst. n.O.K..

1. Check readings of diagnosis in display field - 2 -.

1. "Small leak" or "Large leak".

1. End function "006 - Basic setting" by pressing <-- button.

If system has recognized a small or large leak

1. Check fuel supply and tank ventilation systems for leaks «Checking fuel supply and tank ventilation systems for leaks»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__checking-fuel-supply-and-tank-ventilation) .
2. Afterwards, perform leak diagnosis again.

Checking fuel supply and tank ventilation systems for leaks

Note. The following describes individual areas in the fuel supply and ventilation systems where leaks are possible. After repairing a possible leak, perform a leak test to ensure that leak was successfully repaired.

1. Switch off ignition.
2. Check whether fuel filler cap of fuel tank was completely sealed for test.
3. Check whether seal of fuel filler cap was damaged or crimped. Replace if necessary.
4. Fold rear seat right backrest forward, if necessary.

Wagon

1. Remove luggage compartment cargo floor - 1 -.

Note. Ignore - 2 -.

1. On vehicles without air suspension, unclip right sealing flange cover retainers - arrow -.

1. On vehicles with air suspension, remove spreader pins - arrows - and remove cover - 1 -.

All

1. On vehicles with air suspension, remove bolts - arrows -.
2. Remove pressure tank - 2 - and set aside with line - 1 - connected.

Note. Do not stretch or kink line.

Sedan

1. Release retaining tabs - arrows -.

1. Fold open retaining tabs - 1 - and - 3 - toward rear.
2. Fold cover - 2 - toward front - arrow -.

All

1. Remove cover - arrows -.

1. Remove rear seat bench --> «72 - SEAT - FRAMES»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .
2. Remove cover for locking flange, left and right - arrows -.

Note. Observe installation notes for locking flanges Installing and Installing .

All

1. Check whether seals under locking flanges are OK and union nuts are properly tightened on fuel tank. Also check fuel line connections.
2. Visually check all wires and hose connections of fuel supply system and replace leaking lines, e.g.

1. Line from EVAP canister to Evaporative Emission (EVAP) Canister Purge Regulator Valve N80
2. Lines from EVAP canister to Leak Detection Pump (LDP) V144.
3. Line from fuel tank to EVAP canister (below cover for EVAP canister).
4. Lines for tank ventilation (beneath right rear wheel housing liner).

1. Fuel lines to engine.

Note. Leaks at lines and components of tank system can sometimes be located using a non-flammable, environmentally compliant leak detection spray. For this, initiate leak diagnostic several times in sequence to build up pressure in the system. At leaking areas, bubbles will form.

1. Perform a visual inspection on fuel system components and tank ventilation system

1. Fuel tank
2. EVAP canister
3. Leak detection pump (LDP) V144
4. Evaporative Emission (EVAP) Canister Purge Solenoid Valve N80

Note. Due to the form or function of the components, leaking areas may not always be localized by spraying on leak detection spray. It may be necessary to clamp off the relevant component using Hose Clamps Up to 25 mm dia. 3094 and initiate tank leak detection diagnostic. If the leak is no longer indicated, the component that was clamped off is faulty. If clamped off directly at the leak detection pump and a leak is still indicated, the leak detection pump itself is leaking.

Scheme 87

Special tools, testers and auxiliary items required

1. Portable multimeter V.A.G 1526C
2. Voltage tester V.A.G 1527B
3. Connector test set V.A.G 1594C
4. Adapter cable, 121-pin V.A.G 1598/31

1. Vehicle diagnostic, testing, and information system VAS 5051

Work procedure

1. Ignition switched on.

1. Vehicle Diagnosis, Testing and Information System VAS 5051 connected.

Check activation

Display on VAS 5051

1. Tap "On Board Diagnostic" in selection - 1 - and activate by tapping --> button.

Display on VAS 5051

1. Tap "01 - Engine Electronics" vehicle system in selection - 1 - and activate by tapping --> button.

Display on VAS 5051

1. Tap "005 - Output Diagnostic Test Mode (DTM)" function in selection - 1 - and activate by pressing --> button.

Scheme 88

Display on VAS 5051

A - Output diagnostic test mode waiting, advancing by switching required

1 - Evaporative Emission (EVAP) Canister Purge Solenoid Valve N80

1. Press --> button repeatedly, until Leak Detection Pump (LDP) V144 is activated.

Note. Operating noise of Leak Detection Pump (LDP) is audible at left rear wheel housing.

1. End function "005 - output Diagnostic Test Mode (DTM)" by pressing <-- button.
2. Select "022 - End output" function in selection.
3. Switch off ignition.

If Leak Detection Pump (LDP) for fuel system is not activated (no operating noise audible)

1. Remove leak detection pump (LDP) V144 --> «Leak Detection Pump (LDP) V144 , removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__leak-detection-pump-ldp-v144) and disconnect the electrical connection.

Scheme 89

1. Connect hand multimeter V.A.G 1526C for resistance measurement as follows.

If specifications are not obtained

1. Replace Leak Detection Pump (LDP) V144 --> «Leak Detection Pump (LDP) V144 , removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__leak-detection-pump-ldp-v144) .

If specified values are achieved

1. Check voltage supply of leak detection pump «Checking voltage supply»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__checking-voltage-supply) .

Scheme 90

Note. Voltage for leak detection pump is supplied via Motronic Engine Control Module (ECM) Power Supply Relay J271. Fuse for leak detection pump OK

1. Connect voltage tester V.A.G 1527B as follows

1. Briefly operate starter.

1. LED must light up.

If LED does not light up

1. Check electrical harness connection from terminal - 3 - via fuse to Motronic Engine Control Module (ECM) Power Supply Relay J271 for open circuit according to wiring diagram.
2. Repair open circuit in wiring according to wiring diagram.

Checking output wiring

1. Connect voltage tester V.A.G 1527B as follows

1. Initiate output Diagnostic Test Mode (DTM) «Check activation»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__check-activation) .

Display on VAS 5051

A - Output diagnostic test mode waiting, advancing by switching required

1 - Evaporative Emission (EVAP) Canister Purge Solenoid Valve N80

1. Press --> key repeatedly, until leak detection pump for fuel system is activated.

1. LED must blink.

If LED does not blink

1. End function "005 - output Diagnostic Test Mode (DTM)" by pressing <-- button.
2. Select "022 - End output" function in selection.
3. Switch off ignition.

Scheme 91

1. Connect Adapter cable, 121-pin V.A.G 1598/31 to wiring harness connectors, do not connect engine control module. Connect Ground (GND) clip at test box to Ground (GND) (not visible in illustration) --> «24 - FUEL INJECTION SYSTEM»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-fuel-injection-ignition-engine-codes-bkh) for 3.2 V6 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BKH «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281374-S05905131272008031100000) for 4.2 LITER V8 4V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BVJ 24 - MULTIPORT FUEL INJECTION (MFI) for 4.2 LITER V8 5V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BAT, BNK «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281372-S35275104102008031100000) for 5.2 LITER 10-CYL. 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BXA .

1. Check the following wire connection for open circuit and short circuit to Ground (GND) and B+

1. Repair wiring open circuit or short circuit according to wiring diagram.

If no malfunction is found, but leak diagnosis pump is not functional during output diagnostic test mode

1. Replace Leak Detection Pump (LDP) V144 --> «Leak Detection Pump (LDP) V144 , removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__leak-detection-pump-ldp-v144) .
2. Observe procedures for after re-connecting engine control module (ECM) --> «24 - FUEL INJECTION SYSTEM»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-fuel-injection-ignition-engine-codes-bkh) for 3.2 V6 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BKH «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281374-S05905131272008031100000) for 4.2 LITER V8 4V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BVJ 24 - MULTIPORT FUEL INJECTION (MFI) for 4.2 LITER V8 5V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BAT, BNK «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281372-S35275104102008031100000) for 5.2 LITER 10-CYL. 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BXA .

Checking input wiring

1. Switch off ignition.

1. Connect Adapter cable, 121-pin V.A.G 1598/31 to wiring harness connectors, do not connect engine control module. Connect Ground (GND) clip at test box to Ground (GND) (not visible in illustration) --> «24 - FUEL INJECTION SYSTEM»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-fuel-injection-ignition-engine-codes-bkh) for 3.2 V6 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BKH «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281374-S05905131272008031100000) for 4.2 LITER V8 4V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BVJ 24 - MULTIPORT FUEL INJECTION (MFI) for 4.2 LITER V8 5V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BAT, BNK «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281372-S35275104102008031100000) for 5.2 LITER 10-CYL. 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BXA .

1. Check the following wire connection for open circuit and short circuit to Ground (GND) and B+

1. Repair wiring open circuit or short circuit according to wiring diagram.
2. Observe procedures for after re-connecting engine control module (ECM) --> «24 - FUEL INJECTION SYSTEM»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-fuel-injection-ignition-engine-codes-bkh) for 3.2 V6 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BKH «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281374-S05905131272008031100000) for 4.2 LITER V8 4V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BVJ 24 - MULTIPORT FUEL INJECTION (MFI) for 4.2 LITER V8 5V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BAT, BNK «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281372-S35275104102008031100000) for 5.2 LITER 10-CYL. 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BXA .

Scheme 92

Special tools, testers and auxiliary items required

1. Portable multimeter V.A.G 1526C
2. Voltage tester V.A.G 1527B
3. Connector test set V.A.G 1594C
4. Adapter cable V.A.G 1598/39

1. Test box V.A.G 1598/42
2. Vehicle diagnostic, testing, and information system VAS 5051

Work procedure

1. Ignition switched on.

1. Vehicle Diagnosis, Testing and Information System VAS 5051 connected.

Display on VAS 5051

1. Tap "On Board Diagnostic" in selection - 1 - and activate by tapping --> button.

Display on VAS 5051

1. Tap "01 - Engine Electronics" vehicle system in selection - 1 - and activate by tapping --> button.

Display on VAS 5051

1. Tap "005 - Output Diagnostic Test Mode (DTM)" function in selection - 1 - and activate by pressing --> button.

Display on VAS 5051

A - Output diagnostic test mode waiting, advancing by switching required

1 - Component designation of current activated actuator

1. Press --> button repeatedly, until Leak Detection Pump (LDP) V144 is activated.

Note. Operating noise of Leak Detection Pump (LDP) is audible at left rear wheel housing.

1. End function "005 - output Diagnostic Test Mode (DTM)" by pressing <-- button.
2. Select "022 - End output" function in selection.
3. Switch off ignition.

If Leak Detection Pump (LDP) for fuel system is not activated (no operating noise audible)

1. Remove leak detection pump (LDP) V144 --> «Leak Detection Pump (LDP) V144 , removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__leak-detection-pump-ldp-v144) and disconnect electrical connection.

Checking internal resistance

1. Connect hand multimeter V.A.G 1526C for resistance measurement as follows.

If specifications are not obtained

1. Replace Leak Detection Pump (LDP) V144 --> «Leak Detection Pump (LDP) V144 , removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__leak-detection-pump-ldp-v144) .

If specified values are achieved

1. Check voltage supply of leak detection pump «Checking voltage supply»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .

Checking voltage supply

Note. Voltage for leak detection pump is supplied via Motronic Engine Control Module (ECM) Power Supply Relay J271. Fuse for leak detection pump OK

1. Connect voltage tester V.A.G 1527B as follows

1. Briefly operate starter.

1. LED must light up.

If LED does not light up

1. Check electrical harness connection from terminal - 3 - via fuse to Motronic Engine Control Module (ECM) Power Supply Relay J271 for open circuit according to wiring diagram.
2. Repair open circuit in wiring according to wiring diagram.

1. Connect voltage tester V.A.G 1527B as follows

1. Initiate output Diagnostic Test Mode (DTM) «Check activation»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .

Display on VAS 5051

A - Output diagnostic test mode waiting, advancing by switching required

1 - Evaporative Emission (EVAP) Canister Purge Solenoid Valve N80

1. Press --> button repeatedly, until Leak Detection Pump (LDP) V144 is activated.

1. LED must blink.

If LED does not blink

1. End function "005 - output Diagnostic Test Mode (DTM)" by pressing <-- button.
2. Select "022 - End output" function in selection.
3. Switch off ignition.

1. Connect Test Box V.A.G 1598/42 to wiring harness with adapter cable V.A.G 1598/39-1 or V.A.G 1598/39-2. Clamp test box Ground (GND) clip to battery negative terminal. The procedure will indicate whether engine control module is to be connected to test box or not.

1. Check the following wire connection for open circuit and short circuit to Ground (GND) and B+

1. Repair wiring open circuit or short circuit according to wiring diagram.

If no malfunction is found, but leak diagnosis pump is not functional during output diagnostic test mode

1. Replace Leak Detection Pump (LDP) V144 --> «Leak Detection Pump (LDP) V144 , removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__leak-detection-pump-ldp-v144) .
2. Observe procedures for after re-connecting engine control module (ECM) --> «24 - FUEL INJECTION SYSTEM»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-fuel-injection-ignition-engine-codes-bkh) for 3.2 V6 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BKH «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281374-S05905131272008031100000) for 4.2 LITER V8 4V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BVJ 24 - MULTIPORT FUEL INJECTION (MFI) for 4.2 LITER V8 5V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BAT, BNK «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281372-S35275104102008031100000) for 5.2 LITER 10-CYL. 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BXA .

1. Switch off ignition.

1. Connect Test Box V.A.G 1598/42 to wiring harness with adapter cable V.A.G 1598/39-1 or V.A.G 1598/39-2. Clamp test box Ground (GND) clip to battery negative terminal. The procedure will indicate whether the engine control module is to be connected to the test box or not.

1. Check the following wire connection for open circuit and short circuit to Ground (GND) and B+

1. Repair wiring open circuit or short circuit according to wiring diagram.
2. Observe procedures for after re-connecting engine control module (ECM) --> «24 - FUEL INJECTION SYSTEM»(/audi/a6/6-2004-2008/remont/cooling-fan/#32-v6-4v-fuel-injection-ignition-engine-codes-bkh) for 3.2 V6 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BKH «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281374-S05905131272008031100000) for 4.2 LITER V8 4V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BVJ 24 - MULTIPORT FUEL INJECTION (MFI) for 4.2 LITER V8 5V FUEL INJECTION AND IGNITION, ENGINE CODE(S): BAT, BNK «24 - MULTIPORT FUEL INJECTION (MFI)»(ref-281372-S35275104102008031100000) for 5.2 LITER 10-CYL. 4V FUEL INJECTION IGNITION, ENGINE CODE(S): BXA .

Leak Detection Pump (LDP) V144 , removing and installing

Removing

Note. All cable ties which are opened or cut open when removing, must be replaced in the same position when installing.

1. Remove left rear wheel.
2. Remove left rear wheel housing liner --> «66 - EXTERIOR EQUIPMENT»(/audi/a6/6-2004-2008/remont/door-locks-anti-theft-systems/#body-exterior) .

Scheme 93

1. Remove ventilation hose - 1 -.
2. Remove nuts - arrows -.
3. Disengage diagnostic pump with bracket.

Scheme 94

1. Disconnect electrical harness connector - 3 - with ignition switched off and free up wire - arrow -.
2. Cut cable ties - 1 - and disconnect hose - 2 -.

Installing

1. Tightening torque --> «EVAP canister system/Leak detection system, assembly overview»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .

Installation is in reverse order of removal, note the following

Note. Secure all hose connections using hose clamps appropriate for the model type . During installation, the cable ties must be re-installed at the same location.

1. Secure hose - 2 - to bracket of leak detection pump with cable tie - 1 -.

Scheme 95

1 - Accelerator pedal module

1. With Throttle Position (TP) Sensor G79 and Accelerator Pedal Position Sensor 2 G185
2. Removing and installing --> «Accelerator pedal module with Throttle Position (TP) sensors, removing and installing»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system__accelerator-pedal-module-with-throttle-position)

2 - Electrical harness connector

3 - Bolt

1. 9 Nm

Accelerator pedal module with Throttle Position (TP) sensors, removing and installing

Removing

1. Remove drivers side lower instrument panel cover --> «68 - INTERIOR EQUIPMENT»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .

Scheme 96

1. Disconnect electrical connector - 2 -.
2. Remove bolts - 1 - and - 3 -.
3. Remove accelerator pedal module.

Installing

1. Tightening torque --> «Accelerator pedal module, assembly overview»(/audi/a6/6-2004-2008/remont/fuel-system/#fuel-supply-system) .

Installation is in reverse order of removal, note the following

1. Install drivers side lower instrument panel cover --> «68 - INTERIOR EQUIPMENT»(/audi/a6/6-2004-2008/remont/gauges-instrument-panels/#body-interior) .

Vehicles with automatic transmission

If the throttle position sensor or engine control module are replaced in vehicles with automatic transmission, the kick-down function must be adapted --> Adapting kick-down function after replacing throttle position sensor or engine control module .

Adapting kick-down function after replacing throttle position sensor or engine control module

Note. If the throttle position sensor or engine control module is replaced in vehicles with automatic transmission, the kick-down function must be adapted.

Special tools, testers and auxiliary items required

1. Vehicle diagnostic, testing, and information system VAS 5051 (VAS 5051 B version shown as example only)

Work procedure

1. Vehicle Diagnosis, Testing and Information System VAS 5051 connected with Diagnostic Cable VAS 5051/5A , Vehicle Self-Diagnosis selected.
2. No faults in DTC memory.
3. Engine not running, ignition switched on.

Display on VAS 5051

1. Tap "On Board Diagnostic" in selection - 1 - and activate by tapping --> button.

Display on VAS 5051

1. Tap "01 - Engine Electronics" vehicle system in selection - 1 - and activate by tapping --> button.

Display on VAS 5051

1. Tap "006 - Basic Setting" function in selection - 1 - and activate by pressing --> button.

Display on VAS 5051

1. In button field - 1 - , press buttons 6 3 for "display group 063" and confirm entry by pressing Q button.
2. Activate basic setting by pressing Activate button - A -.

Display on VAS 5051

1. Check indication in display fields - 3 - and - 4 -.
2. After display "Activate kick-down" appears, depress gas pedal all the way down beyond kick-down point and hold it there.

Note. "ERROR" could be displayed e.g. if the accelerator pedal is not immediately depressed after prompting the VAS 5051 or if the accelerator pedal is released during adaptation, even though adaptation had not been completed. Exit the function "006 - Basic setting" by pressing <-- button and perform adaptation again.

1. End function "006 - Basic setting" by pressing <-- button.
2. Select "022 - End output" function in selection.
3. Turn ignition off and disconnect Data Link Connector (DLC).

See also:
• 24 - FUEL INJECTION SYSTEM
• 27 - STARTER, GENERATOR, CRUISE CONTROL
• 72 - SEAT - FRAMES
• 66 - EXTERIOR EQUIPMENT
• 39 FINAL DRIVE, REAR DIFFERENTIAL
• 39 - FINAL DRIVE, DIFFERENTIAL
• 42 - REAR SUSPENSION
• 26 - EXHAUST SYSTEM, EMISSION CONTROLS
• Fuel tank, emptying
• Installation position of Ground (GND) connection
• Fuel tank with attachments, removing and installing
• B - Emptying a fuel tank less than 1/4 filled
• Safety precautions
• Fuel delivery unit, removing and installing
• Evaporative emissions (EVAP) canister, removing and installing
• Fuel Level Sensor G , checking
• Fuel Level Sensor G , removing and installing
• Suction jet pump, removing and installing
• Fuel Level Sensor 2 G169 , checking
• Installing
• Fuel Pump (FP) Control Module J538 , removing and installing - Vehicles with FSI engine
• Fuel filter, removing and installing
• Installed location
• Leak Detection Pump (LDP) V144 , removing and installing
• Diagnostic leak test, performing
• Checking fuel supply and tank ventilation systems for leaks
• Checking voltage supply
• Check activation
• Accelerator pedal module with Throttle Position (TP) sensors, removing and installing
• Adapting kick-down function after replacing throttle position sensor or engine control module