Checking fuel tank system and tank breather system for leaks — AUDI

🧭 Before you start

Fits: Audi TT Mk1 (8N)

• Renewed: if necessary, leaking pipes/hoses, o-rings

Don't miss

• Observe notes on installing flanges , and .

🔧 Engine codes this applies to

📐 43 workshop diagrams for AJQ

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

📋 Procedure

1. Switch off ignition.
2. Check whether the filler cap of the fuel tank was properly closed when performing the diagnosis.
3. Check whether the seal of the filler cap is damaged or deformed. Renew if necessary.
4. Remove rear seat bench 72.
5. Remove back panel side trim (right-side) 70.

6. Unscrew cover (1) for flange (right-side) (arrows).
7. Remove back panel side trim (left and right) 70
8. Unscrew cover (1) for flange (left and right) (arrows).
9. Check whether the seals on the flanges are damaged and whether the union nuts on the fuel tank flanges are properly tightened. Also check whether the fuel lines are connected properly. [Note: Observe notes on installing flanges , and .]
10. Perform a visual check on all pipe/hose connections of the fuel tank system and renew leaking pipes/hoses, e.g.: [Note: Leaks in pipes and components of the fuel tank system can sometimes be detected by applying a non-flammable, environment-friendly leak detecting spray. Initiate a tank leak diagnosis repeatedly to build up pressure in the system. Bubbles will form at the leak.]
11. Perform a visual check on the components of the fuel tank system/fuel tank breather system: [Note: Due to the shape or function of these components it is not always possible to detect leaks by applying leak detecting spray. If this is the case, clamp off hoses going to the respective component using hose clamps 3094 and initiate tank leak diagnosis. If no leak is then found after clamping off the hoses, the corresponding component is defective. If the hoses are clamped off directly at the diagnostic pump and a leak is still indicated, there is a leak in the diagnostic pump itself. Check activated charcoal filter solenoid valve 1N8024.Renew O-rings if activated charcoal filter solenoid valve 2N115 is leaking .]
12. Install rear seat bench 72.
13. Install back panel side trim 70.

Other AUDI procedures

• Renewing inlet camshaft oil seal – Audi A6 C5
• Checking function of variable valve timing – Audi A4 B5
• Testing lambda probe and lambda control (before catalytic converter)
• Checking oil pressure and oil pressure switch F1 – Audi TT Mk1
• Checking turbocharger and charge pressure regulating valve - vehicles with electronic throttle
• Removing and installing toothed belt – Audi · 56 torque figures
• Removing engine – Audi A8 D3 · 41 torque figures
• Removing camshaft timing chain from camshafts – Audi A6/A7 C7 · 38 torque figures
• Installing engine – Audi A8 D4 · 36 torque figures
• Removing and installing camshaft timing chain · 29 torque figures