Function and tightness of secondary air combination valve, checking: Requirements
WARNING: This page is about a different car, the 2006 Audi A4, 2005 Audi A4, 2004 Audi A4, and 2003 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.
- No leaks along vacuum hoses or at hose connections.
- No obstructions in vacuum hoses.