My car doesn't heat up anymore and I think it's because my Thermostat is stuck open. Anyone know how to go about fixing this? 01 B5 1.8

 

Just replace it. They are cheap.

 

Could be your temp sensor too. Those are equally cheap - about $15

 

b4 u go spend money on anything, do some tests. have ur engine cold and then start it, put a thermometer in the reservoir and see wut temp u get when the coolant starts to flow. u don't need to do this if the coolant starts to flow as soon as u start the engine. not sure wut temp the 1.8 runs as but it should be around 170 i think. like wood_e said it could be ur temp sensor. and it's only $7 at autozone. and the thing that sends is the temp sensor so im guessing that is probably ur #1 culprit unless u got a bad gauge or sm.