I have a 99 328i sedan E46 manual. Just yesterday, I noticed the
radiator fan stayed on even after I had turned off the car. I know
there is a sensor watching temperatures and it is supposed to continue
to run for a while if needed, so I ignored it.

Came out this morning to a dead battery. Swapped out batteries and the
radiator fan starts running even before I can turn the car on. Hmm...
faulty sensor, I bet.

Anyone know which sensor I should be looking for? The radiator sensor
in the lower hose? Or is the thermostat in the water pump connected to
this fan, too?

Thanks!