I replaced my sender with a cheapy
from some where, it read low after that.
These senders are in a vulnerable spot,
easy to break off the spade terminal, so
I bet you got a new one too, I broke mine
off trying to tighten it up, the terminal was
loose and rotating on the pin, making the
guage read wierd and all over.
Brand New temp guage read straight up
middle, never moved from there once warmed up