Checking fuel tank system for leaks - R8 Coupé: Audi 4.2 (BUJ, BYH, CMPA, CNDA, …)

🧭 Before you start

Fits: platform code 42

• Special tools named: VAS 6615

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• If specified values are obtained, VAS 6615 is OK and check can be performed.If specified values are not obtained, VAS 6615 is defective and must be renewed.

🔧 Engine codes this applies to

📋 Procedure

1. Connect tank leak tester (Audi R8)VAS 6615 to compressed air (6 ... 10 bar) (item 1).
2. Open cut-off valve (2) (handle should be horizontal).
3. Read off value indicated on display of tester:
4. Close cut-off valve (handle should be vertical). [Note: If specified values are obtained, VAS 6615 is OK and check can be performed.If specified values are not obtained, VAS 6615 is defective and must be renewed.]
5. ⚠ If value displayed on VAS 6615 exceeds 200 mbar during the function check or during the subsequent pressure test, the device is defective and must be disconnected from the compressed-air connection immediately. — Remove engine compartment trim panel (right-side) 53.

6. Unbolt engine control unit (right-side) from bracket (arrows).
7. Slacken bolts (arrows) a few turns.
8. Remove bolt (2) and detach bracket (1) for engine control unit (right-side).
9. Press release tabs and detach breather hose (arrow) leading to fuel tank from activated charcoal filter (1).
10. Seal detached hose with plug (1) from VAS 6615.
11. Remove filler cap from fuel filler neck.
12. Screw adapter (1) from VAS 6615 into fuel filler neck.
13. Connect compressed-air connecting line (2) from VAS 6615 to adapter from VAS 6615.
14. Open cut-off valve (handle should be horizontal).
15. After waiting approx. 5 minutes, check pressure in fuel tank; to do so, close cut-off valve on VAS 6615 (handle should be vertical).
16. Read off value indicated on display of tester:
17. After waiting approx. 2 minutes, check pressure in fuel tank again; to do so, read off value displayed on tester:
18. If specification is not attained, use leak-detecting spray to locate leak and seal off. Repeat leak test.
19. If specification value is obtained, disconnect VAS 6615 from compressed-air connection and remove from fuel tank.
20. Install engine compartment trim panel (right-side) 53.
21. Install side panel trim (with tank flap unit) 53.

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