Checking pressure retention valve in fuel return line: Audi A8 D3 (ASB, BKN, BMC, BMK, …)

🧭 Before you start

Fits: Audi A8 D3 (4E, 2002–2010)

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• Always read rules for cleanliness and instructions for working on fuel system .Follow these instructions before starting work and while working on the fuel system. — Remove engine cover panel .
• Clean return line connection on cylinder 1 (with commercial cleaning solution or similar) before removing.
• Take care to keep all components clean. No dirt must be allowed to get into the disconnected return line or the open connection on the injector.
• Lubricate all seals with engine oil or assembly oil before installing.

🔧 Engine codes this applies to

📋 Procedure

1. ⚠ Always read rules for cleanliness and instructions for working on fuel system .Follow these instructions before starting work and while working on the fuel system. — Remove engine cover panel .
2. Clean return line connection on cylinder 1 (with commercial cleaning solution or similar) before removing.
3. Dry return line connection on cylinder 1.
4. Cover return line connection on cylinder 1 with a cloth.
5. Pull return line connection off cylinder 1; to do so, press both tabs down and at the same time pull centre piece up to release connection (arrow). [Note: Take care to keep all components clean. No dirt must be allowed to get into the disconnected return line or the open connection on the injector.]

6. Connect tester for fuel return systemVAS 6330 between return line connection on injector and return line.
7. Start engine.
8. Check pressure indicated on tester.
9. Renew O-ring for return line connection. [Note: Lubricate all seals with engine oil or assembly oil before installing.]
10. Push the return line connection carefully over the new seal and onto the injector. The catch should engage audibly. Then press release pin down carefully.
11. Erase entry in event memory using a diagnostic tester.
12. Check fuel system for leaks.

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