Checking exhaust gas recirculation valve N18: Audi A8 D2 (ACV, AFB, AFN, AGX, …)

🧭 Before you start

Fits: Audi A8 D2 (4D)

Don't miss

• Connect adapter cable, 121-pinV.A.G 1598/31 to connector of wiring harness (do not connect engine control unit).

🔧 Engine codes this applies to

📋 Procedure

1. From menu (1), select diagnostic function "“Interrogate fault memory”" and press → key to continue.
2. Press ← key to terminate function "“Interrogate fault memory”".
3. Switch off ignition.
4. Unplug electrical connectors (1 ... 4).
5. Disengage connector (3) from bracket.

6. Slide charge pressure control solenoid valve N75 and exhaust gas recirculation valve N18 off bracket in direction of (arrow).
7. Detach hose at vacuum connection (3) (leave hose at connection (2) attached to mechanical exhaust gas recirculation valve).
8. Connect hand vacuum pumpVAS 6213 to vacuum connection (3).
9. Use a test lead from auxiliary measuring setV.A.G 1594C to connect contact (2) of solenoid valve to battery positive "“+”".
10. Connect contact (1) to earth.
11. Detach caps on engine cover panel.
12. Unbolt and remove engine cover panel (arrows).
13. Disconnect vacuum hose from mechanical exhaust gas recirculation valve (arrow).
14. Operate hand vacuum pumpVAS 6213.
15. Detach earth connection from contact (1) of solenoid valve.
16. Operate hand vacuum pumpVAS 6213.
17. Renew exhaust gas recirculation valve N18.
18. Connect hand-held multimeterV.A.G 1526D for voltage measurement as follows:
19. Switch on ignition.
20. Check wiring connection for open circuit and short to positive or earth .
21. Unplug electrical connector (arrow) at exhaust gas recirculation valve N18.
22. Connect multimeter (resistance measuring range) to valve.
23. Renew exhaust gas recirculation valve N18.
24. Slacken off cross-head bolts (1) at electronics box in plenum chamber.
25. Unclip plenum chamber cover (2) at front of bulkhead (arrows).
26. Detach plenum chamber cover.
27. Prise out cover (1) in cowl panel trim and loosen rear cross-head bolt (arrow) at rear right.
28. Slacken off the remaining cross-head bolts (arrows).
29. Detach cover for electronics box (plenum chamber).
30. Connect adapter cable, 121-pinV.A.G 1598/31 to connector of wiring harness (do not connect engine control unit).
31. Connect earth clip of adapter cable to earth (not shown in illustration).
32. ⚠ Electronic components are susceptible to damage.Select the appropriate measuring range before connecting the test leads and observe test requirements. — Check for open circuit and short to positive or earth in the following wiring:
33. Repair wiring connection if necessary.

Other AUDI procedures

• Checking intake manifold pressure sender G71 and altitude sender F96
• Checking charge pressure control – Audi A4 B5
• Checking injectors
• Checking coolant temperature sender G62
• Checking clutch pedal switch F36 – Audi A6 C5
• 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