So, as I was finding the location of the Engine Coolant TEMPERATURE sensor since its starting to give me problems intermentantly i found that it was located at the back of the engine block.... However i also noticed there was a sensor sitting at the bottom of the coolant overflow. The service manual says its a ECL (Engine Coolant Level) warning switch... which surprised me cause there is no coolant level warning light on the dash (i have the 6, not the 4 big ones, center dummy lights pre '99 A4).

Does anyone know what happens when the level gets too low, does it turn on the overheat light or the service engine soon light or what?

 

Figured it out it just turns on the overheat light i guess.