Make sure the expansion tank, and reservoir are both filled with
coolant.

If this doesn't solve the problem clean the level sensor probe with CLR.
It just may be full of crud and not working properly.

This is a pretty common happening if either of the above isn't right.

RC

<<Subject: Temp gauge on hot at cold startup
My temp gauge needle is shooting all the way up on cold startup. Also
the red dummy lite is blinking on and off. I have plenty of fluid, and
symptoms occurred on cold start-up---any ideas?
Thanks----G.>>