Checking fuel system pressurisation pump G6 (in fuel tank) - A5 from model year 2012 onwards, A4 from model year 2013 onwards (vehicles with front-wheel drive and vehicles with four-wheel drive) — AUDI

🧭 Before you start

Fits: Audi A5 (8T, 2007–2016), Audi A5 Cabriolet (8F), Audi A4 B8 (8K, 2007–2015)

• Special tools named: VAS 6551, VAS 6551/5

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• Risk of fuel escaping.Cut-off valve (C) must be closed.The lever should point perpendicular to direction of flow. — Connect vehicle diagnostic tester.
• From this point on, do not turn adjuster screw (1).
• To find the precise cause of the fault, a pressure test must be performed on the fuel supply line as described below.
• Risk of fuel escaping.Cut-off valves (B and C) must be closed.The levers should point perpendicular to direction of flow. — Press Start on vehicle diagnostic tester display to start the fuel pump.
• In this way the pressure tester (diesel)VAS 6551 is connected into the fuel supply line.

🔧 Engine codes this applies to

📐 38 workshop diagrams for CAGA

Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.

📋 Procedure

1. Observe test conditions .
2. Open tank flap.
3. Remove filler cap (arrow) for fuel filler neck.
4. ⚠ The fuel can become extremely hot. This can cause injuries.In extreme cases the fuel lines and the fuel can reach a temperature of 100 °C. Allow the fuel to cool down before disconnecting the lines - danger of scalding.Wear protective gloves.Wear safety goggles.Risk of injury - fuel system operates under high pressure.To reduce the pressure in the fuel system, wrap a clean cloth around the connection and carefully loosen the connection. — Release hose clip (2) and detach fuel supply hose (1) leading to high-pressure pump from fuel supply line (3).
5. Connect pressure tester (diesel)VAS 6551 to fuel supply line with connecting lineVAS 6551/5-2 and secure with hose clip.

6. Attach pressure control valveVAS 6551/6 and hold end of hose into fuel-resistant measuring container.
7. Switch on pressure tester (diesel)VAS 6551(item 1) by pressing On/Off button. [Note: To measure the fuel delivery rate, pressure must first be built up in the fuel supply line; the fuel pump must then operate against this pressure during the measurement. This pressure can be built up using the pressure control valveVAS 6551/6 as follows:]
8. Open cut-off valves (A and B).
9. ⚠ Risk of fuel escaping.Cut-off valve (C) must be closed.The lever should point perpendicular to direction of flow. — Connect vehicle diagnostic tester.
10. Switch on the ignition and select the following menu options on the vehicle diagnostic tester:
11. Press Start: The fuel pump will start running.
12. Build up pressure in fuel system by turning adjuster screw (1) on pressure control valveVAS 6551/6 until correct pressure is reached.
13. From this point on, do not turn adjuster screw (1).
14. Press Stop.
15. Drain measuring container.
16. For measurement, press Start again and let fuel pump run for 15 seconds.
17. Press Stop after 15 seconds.
18. Check amount of fuel delivered in measuring container. [Note: To find the precise cause of the fault, a pressure test must be performed on the fuel supply line as described below.]
19. Switch on pressure tester (diesel)VAS 6551(item 1) by pressing On/Off button.
20. Open cut-off valve (A).
21. ⚠ Risk of fuel escaping.Cut-off valves (B and C) must be closed.The levers should point perpendicular to direction of flow. — Press Start on vehicle diagnostic tester display to start the fuel pump.
22. Press Stop after 15 seconds.
23. Read fuel pressure off pressure tester (diesel)VAS 6551. [Note: To detect any faults in the fuel return line or in the relief valve of the high-pressure pump, a pressure test must be performed on the entire system as described below.Before disconnecting the measuring equipment, release the fuel pressure by opening the cut-off valves (B and C) and allowing fuel to drain off into a measuring container.]
24. Detach pressure control valveVAS 6551/6 and remove together with measuring container.
25. Attach connection fittingVAS 6551/5-1 to fuel supply hose (2) leading to high-pressure pump, secure with hose clip and attach connecting lineVAS 6551/5-4.
26. Attach connecting lineVAS 6551/5-3 and VAS 6551/5-4 to pressure tester (diesel)VAS 6551. [Note: In this way the pressure tester (diesel)VAS 6551 is connected into the fuel supply line.]
27. Switch on pressure tester (diesel)VAS 6551(item 1) by pressing On/Off button.
28. Open cut-off valves (A and B).
29. ⚠ Risk of fuel escaping.Cut-off valve (C) must be closed.The lever should point perpendicular to direction of flow. — Switch on the ignition and select the following menu options on the vehicle diagnostic tester:
30. Press Start: The fuel pump will start running.
31. Read fuel pressure off pressure tester (diesel)VAS 6551. [Note: Before removing the pressure tester (1), release the fuel pressure by opening the cut-off valves (B, C) and allowing fuel to drain off into a measuring container.]
32. Detach pressure tester (diesel)VAS 6551 together with connecting lines.
33. Secure fuel supply line with hose clip and then pull to check that fuel supply line is properly secured.

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