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.
Fig 1: Identifying Special Tools - Cooling System, Checking For Leaks
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Special tools, testers and auxiliary items required