WARNING: This page is about a different car, the 2009 Audi A4, 2008 Audi A4, 2007 Audi A4, 2006 Audi A4, and 2005 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Locating Bolt For Camshaft Sprocket And Retainer 3036
Courtesy of VOLKSWAGEN UNITED STATES, INC.
When loosening and tightening centered bolt, use Retainer 3036.