Engine Contaminants

WARNING: This page is about a different car, the 2009 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

To prevent foreign objects from entering when working on the engine, seal open intake and exhaust channels with suitable plugs, for example from the Engine Bung Set VAS6122.
If mechanical damage to a cylinder bank is found, check the intake and exhaust tract and the combustion chambers in the opposite cylinder back for foreign objects to prevent further damage.