05 Yukon 5.3L - sensor testing?

[Gary]

Got a CEL and had Oreilly's pull the code, "coolant temperature too low" or something like that. Idiot gauge says it runs around 180F so surely that's not too low? So I'm guessing coolant temperature sensor failure? How do I test it to be sure? Don't want to replace something what ain't broke.

It's the sensor on the driver side head right? Going by this diagram #7:

http://www.worldwidecamaroclub.com/pdf/engine.pdf

I assume when I pull that sensor out I'm gonna lose coolant right (assuming the sensor is bad and the cause for my code)?