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Checking delivery pressure of fuel system pressurisation pump G6 — VW

Checking delivery pressure of fuel system pressurisation pump G6 on VW: 31 steps, engines CAYB, CAYC, CBAA, CBAB.

This check measures what the fuel system pressurisation pump G6 delivers on the common-rail TDI engines listed, a page merging several variants built on platform code 601. A pressure tester is teed into the fuel feed at the fuel filter, between the filter and the high-pressure pump, and the pump is run through the diagnostic tester's guided function. Pressure is read with the pump activated, at idle and at 2500 rpm. If it falls short, the tester is moved upstream of the filter, and then to the delivery unit outlet in the tank, to isolate a blocked filter or a weak pump. The deciding points are safe pressure relief at every connection and checking the delivery unit connector before condemning parts.

31 steps 21 engine codes engine codes merged from 4 documented variants

🧭 Before you start

Relieve pressure with a cloth around each joint, then fit the tester between the fuel filter and the high-pressure pump. Activate the fuel pump through the guided function and read pressure; then repeat at idle and at 2500 rpm, with a minimum of 4.5 bar each time. If low, measure upstream of the filter; if that passes, renew the filter. If still low, test at the fuel delivery unit, where 7.2 ± 0.5 bar is specified, and check the connector before renewing the supplementary filter with its pressure regulator.

Fits: platform code 601

  • Special tools named: VAS 6551/1, VAS 6551/2

Don't miss

  • Wrap a cloth around each connection and ease the hose off slowly to release pressure.
  • Minimum 4.5 bar at the filter outlet with the pump activated, at idle and at 2500 rpm.
  • At the fuel delivery unit the specification is 7.2 ± 0.5 bar.
  • Pull-check the delivery unit connector without pressing its catch; a loose plug can cause the fault.
  • Mount the gauge on the windscreen so it can be read from the driving seat.

Written for this job from the workshop steps below · TorqFix editorial.

🔧 Engine codes this applies to

CAYBCAYCCBAACBABCBBBCBDACBDBCBDCCFFACFFBCFGBCFGCCFHBCFHCCFWACJAACLCACLJACLNACWXACWXB

📋 Procedure

  1. ⚠ Fuel supply line is pressurised. Wear eye protection and protective clothing to avoid eye injuries and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection. — Remove engine cover Removing and installing engine10Removing and installing engine cover.
  2. Push the push-on connector coupling at the fuel filter, the fuel supply line to the high-pressure pump, forwards onto the filter connection. Press catches in and hold, pull fuel supply line from fuel filter. Separate connectors .
  3. Collect escaping fuel with a cleaning cloth.
  4. Connect pressure testerVAS 6551 to lines VAS 6551/1 and VAS 6551/2 in fuel circuit.
  5. Switch on pressure testerVAS 6551 by pressing On/Off button.
CAYB? Steps differ between engine variants — check this job against your exact car before you commit to it. Check my car — free →
  1. Open shut-off taps "“A”" and "“B”" of pressure testerVAS 6551 and close shut-off tap "“C”".
  2. Connect vehicle diagnosis tester and carry out guided function "“Fuel pump activation (checking fuel pump)”". [Note: The fuel pump is now activated for 30 seconds.]
  3. Read pressure on pressure testerVAS 6551. Specification: min. 4.5 bar.
  4. Start engine and run at idling speed.
  5. Read pressure on pressure testerVAS 6551. Specification: min. 4.5 bar.
  6. Place pressure testerVAS 6551 onto windscreen so that it can be read from inside of vehicle.
  7. Increase idling speed to 2500 rpm.
  8. Read pressure on pressure testerVAS 6551. Specification: min. 4.5 bar
  9. Reconnect fuel supply line to high-pressure pump at fuel filter.
  10. Push plug-in connector on fuel filter fuel delivery line to fuel filter, forwards onto filter connection.
  11. Press catch in and hold, pull fuel supply line from fuel filter. Separate connectors .
  12. Collect escaping fuel with a cleaning cloth.
  13. Connect pressure testerVAS 6551 with lines VAS 6551/1 and VAS 6551/2 to open ends.
  14. Perform pressure measurement as in previous check.
  15. The fuel filter must be renewed .
  16. Reconnect push-on coupling to fuel filter.
  17. Raise cover of fuel delivery unit.
  18. First check that connector (arrow) is fitted securely by pulling connector without pressing catch. The connector can cause a fault if it has not been fitted correctly.
  19. Pull fuel supply line (black or black marking) (4) off fuel delivery unit. Separate connectors .
  20. Collect escaping fuel with a cleaning cloth.
  21. Connect connection (A) of pressure testerVAS 6551 with line VAS 6551/1 to open end of fuel delivery unit.
  22. Open shut-off taps "“B”" + "“C”" of pressure testerVAS 6551.
  23. Switch on pressure testerVAS 6551 by pressing On/Off button.
  24. Connect vehicle diagnosis tester and carry out guided function "“Fuel pump activation (checking fuel pump)”". [Note: The fuel pump is now activated for 30 seconds.]
  25. Read pressure on pressure testerVAS 6551. Specification: 7.2 ± 0.5 bar.
  26. Replace supplementary fuel filter together with integrated pressure regulator.

Other VW procedures

Who makes these pages, and how

TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.

The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.

Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.

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Workshop data on this page last updated 20 Sep 2026.