Poor or faulty oxs sensors on all VW & Audi's can cause numerous problems without setting a check engine light. Typically owners do not notice the decrease in performance driveability or fuel economy till the problem gets really noticeable. Air mass sensor usually die a slow death so most customers notice a huge improvement in performance smoothless & fuel economy when replacing their faulty oxs sensor with a new one.
Replacing oxs sensors is one know solution for "lean" or "rich" engine codes
This Part Fits the Following Vehicles