Checking non-return valve and vacuum hoses to valves N125 and N126 — AUDI
Checking non-return valve and vacuum hoses to valves N125 and N126 on Audi: 18 steps, engines CAAA, CAAB, CAAC, CAAD.
Workshop procedure for AUDI — the exact step sequence and torque figures, straight from real workshop data.
🧭 Before you start
Fits: VW Transporter T6 (7F), VW Transporter T6 (7E)
- Renewed: leaking vacuum hose
📋 Procedure
- Pull vacuum hose (3) off T-piece (4).
- Connect hand vacuum pumpVAS 6213 to removed end of vacuum hose and generate a partial vacuum of 0.6 bar.
- Observe pressure gauge of hand vacuum pumpVAS 6213 for approx. 30 seconds.
- Pull vacuum hose (1) off non-return valve (2).
- Seal opening of non-return valve with clean bung from engine bung setVAS 6122.
- Connect hand vacuum pumpVAS 6213 to pulled-off vacuum reservoir and generate a partial vacuum of 0.6 bar.
- Observe pressure gauge of hand vacuum pumpVAS 6213 for approx. 30 seconds.
- First pull vacuum hose off at hand vacuum pumpVAS 6213.
- If the non-return valve functions properly, a clear hiss is audible when vacuum in vacuum hose is released.
- Renew vacuum hose (1) or non-return valve (2) if they leak.
- Push vacuum hose onto non-return valve.
- Remove front left underbody cover General body repairs, exterior66Underbody cover; Removing and installing underbody covers.
- Pull vacuum hose (arrow) off connector. Seal opening of vacuum hose with clean bung from engine bung setVAS 6122.
- Connect hand vacuum pumpVAS 6213 to pulled-off vacuum reservoir and generate a partial vacuum of 0.6 bar.
- Observe pressure gauge of hand vacuum pumpVAS 6213 for approx. 30 seconds.
- Renew leaking vacuum hose.
- Reconnect vacuum hose to connecting piece and non-return valve.
- Check following vacuum hoses:
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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.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
The story behind TorqFix →Workshop data on this page last updated 20 Sep 2026.