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: Left Holder For Connectors On Bulkhead
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To Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) G131