Where is the thermostat located on a 2004 VW 1.8L GTI?

The thermostat on a 2004 VW 1.8L GTI is located at the engine end of the upper radiator hose, where it connects to the engine block. To access it, you typically need to remove the upper radiator hose and the thermostat housing, which is secured by bolts. Make sure to allow the engine to cool and drain some coolant before starting the replacement process.