My car: Audi b6 2003, 1.6l benzin

Saturday i tried to fix my temp gauge, by shifting the tempsensor (g62), here i also shifted the whole tempsensor house, because it was leaking. After i had put everything back on place, and shifted the coolant, i started the engine and noticed that the fan startet up on full throttle, and when i stopped the car the fan seem to just go on forever, so i had to just pull out the plugg...

Anyone got any ideas what the hell is wrong?

I also found this sensor?? Which was mounted under the thermostat. It was verry "crispy" and old, it clearly needed replacement, but i have no idea what it is! Any idea what this is:

 

anyone? Where does the fan got its signals from?