Found something while fixing horn, PART 1

While accessing my horns to fix a broken horn wire, I came across another broken wire leading to this sensor (one pic attached) which appears to be tapping into the coolant loop. The view in the picture is looking up from the driver’s side front open wheel well. (The wire is broken in two places, once at the connector, and completely severed out of the picture frame.) I have two questions –

what is this sensor or actuator?

and

why do I not have any error messages or problems from it?

Everything seems to be working fine; gauges, heater, etc. Any info or guidance would be appreciated.

Attached Images

 

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2006 X5 4.8is
LeMans Blue over black
Style 168 rims
Blackout grills and hood vents
Aux jack