Is it tough to install a new coolant temperature sensor into a 2005 Bonneville GXP? How do you do it? Is it under the water pump or where?

I believe its under the thermostat housing. Everything on this engine is a bear to get at. There hasnt been a temp sensor problem I can recall here in the forum as of yet.

i have got one now that the gauge works fine til after car gets warmed up. then it reads 280. turn car off and it sticks at some other random number. if you repeat turning it on and off it sticks whereever on gaue. so i assume it is the sensor

It might be the guage cluster. The fuel and temp gauges have stepper motors so they can sweep back and forth when the ign is turned on. I have had to replace mine already for the fuel gauge messing up like you described your temp guage was. Just a suggestion.

How much work is it to install a new stepper motor? My boost gauge stops at around 2 psi of boost and I know I get about 6-8 psi out of it

Chad, did you find a stepper motor or have to replace the cluster. I was under the impression you have to replace the whole thing?

Your right. The whole cluster had to be replaced for my problem, about $600.00 for the cluster not counting labor .

Ya, and that SUX! GM really put the Screw to us with this one. Everytime one little thing goes wrong with the cluster, they designed it to be replaces as a whole unit. I bet they have about 100K of them stacked up waiting for warranty'* to go down. Would be nice if an electronic minded member came along and could get us an easy fix for these. It'* a problem coming up more and more.