Valves, Checking
WARNING: This page is about a different car, the 2016 Audi Q3 Quattro, 2016 Audi Q3, 2015 Audi Q3 Quattro, and 2015 Audi Q3. However, it is still accessible from the selected car via links, so may be relevant.
-- Check valves at stem and seating surface for traces of wear.
-- If there are clear traces of wear, replace valve.