Water temp guage reading

I have a 2002 4.7L with 155,000 miles. The water temp guage has always read 1/3, but jumped to 1/2 all at once. The scanner shows the water temp guage reading at the middle with the scanner reading 150 degs to 190 degs. The outside temperature is about 75 degs.
I would like to know why the guage reading changed. The fan clutch seems to have the same resistance hot or cold. When I shut the engine off, the fan continues to turn about 2 revs. The coolant is clean, with Toyota anti freeze and distilled water. The radiator core is clean.
Any suggestions would be appreciated.

Thanks,
Ken

 

The gauge sensor is different than the ECU sensor. I'd say keep an eye on the temp on your scan tool and make sure it is at a reasonable level.
Pic from @Tundra2

 

Just adding to an already-great reply for search purposes. Location is here on the earlier (non-VVTi, '00-'04?) models, to the passenger side of the throttle body. Two sensors, one for ECU to gauge temps, one for your dash gauges. Stick with OEM on this part (per rule of thumb: always use OEM on electrical sensors specifically).

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If your engine is hot and you can spin the fan by hand and it goes more than a 1/4 rotation, it's poop. Get a new one.

It should basically not spin at all when hot. It'll feel free, but like it's trying to spin in super compact grease it just stops immediately.