Yes , I believe a faulty coolant level sensor can cause your gage to read
inaccurate.My gage read low. One day the sensor blew out of the tank,and I
replaced it.As a side effect, and unexpectedly, my temp gage now read
normal. Closer inspection of the old sensor showed  that one black plastic
probe had cracked all the way around. I guess this caused some kind of
short circut.