I don't see cold weather package in your sig...if you had headlight washers, that would be the three pumps. There is only one sensor though, towards the front of the reservoir. I recommend waiting until your fluid actually is low before trying to clean it or replace it.
Part #17137553919, see #6 in this diagram

__________________
*********************
Olympic Peninsula, WA, USA
-----------------------------------------
2005 Mini Cooper 100k, British Racing Green/Silver-Black
04/2002 4.6is 140k, Silver/Black-Alcantara *FOR SALE*
1989 325iX 270k, Diamond Black/Black
1984 318i 370k *SOLD* (First Bimmer)
Honorable Mentions: '71 2002, '87 325, '90 325ic, '92 525it, '93 325i, '94 530i