My 09 VW CC check engine light is on

My suggestion is have it scanned yet again. For one thing, no OBD scan can say thermostat..there are codes about coolant temperature but none, not even the best scanner can pin-point thermostat. Sure, the light can be turned off with a scanner, but that solves nothing. And the CEL light coming on a mistake? he is taking you for a fool my friend and if you don't know cars, we all have our areas of things, he flat insulted you. The fault remained, whatever it was so the light re- appeared. Go to AutoZone or someplace like that, get the codes, DON'T buy anything, come back here with the codes and tell us.

A faulty, loose or missing gas cap will cause the CEL to light up. A 2009 is really too soon to begin to have throttle body problems...but meantime don't just buy the cheapest gas. Buy Brand-name like Shell, Chevron. any of the big ones, the small independent refineries that sell to convenience stores and independent retailers don't have the detergents your car needs

Check out this article on Common Causes that trigger VW check engine light. https://www.youcanic.com/guide/volkswagen-check-engine-light