That is NOT the gauge sensor ..

Gauge sensor is single pin

http://catalog.eautopartscatalog.com/mercedesshop/sophio/image.jsp?title=Water%20Temperature%20Sender&url=http%3A//img.eautopartscatalog.com/live/P403612281FAE.JPG

Here are the specs for checking it's calibration

60C-110 ohm
80C -67
100C - 38

You can also sub a Radio Shack 1% resistor of one of these values to test the accurcy of the guage I use the 67 ohm for best results.
Or , you can ohm sensor at different temp and make gauge/chart comparisons