I have a 01 SE and my service engine soon light is on. It came on about two months ago, and my friend hooked it up to his snap on scanner. It shot a thermostat code. He reset it and the light stayed off until now. My question is, if it shot the thermostat code and the engine temperature gauge reads around 150, am I safe in assuming that i need to replace my thermostat? If so, can someone tell me where it is located and if there is anything I need to know about replacing it (other than the usual two bolt and a gasket way that every other car that i have worked on has)? Thanks guys

See where your radiator hose goes in on the the top of the engine? It'* under that housing. By the sound of your problem, sounds like a stuck open t-stat.

If the digital gauge is reading 150 degrees you're probably collecting a lot of unburned stuff on the walls and into the oil. It'* not good.

You can drain a little coolant out of the radiator with a siphon hose,
remove the two bolts holding the thermostat housing on at the end of the upper radiator hose- I don't even remove the hose from the metal housing,
remove the thermostat with it'* rubber ring that seals it
replace with a new GM Delco which will come with the rubber ring, IIRC
be sure to put the pellet end into the upper manifold like the one you take out was
carefully thread the two bolts back on being careful not to cross thread (I did)
tighten to about the same as the ones you took off
refill the coolant into the radiator
replace cap
run motor to heat up
after bottom radiator hose is warm (after a good drive) rev motor to 2500 rpm 5 times to get air out of heater core--it helps if car is up slight slope forward to help air flow uphill to radiator
carefully open screw on top of thermostat housing to let air out of that point -- I hold a shop towel over the screw but it has never spewed out on me, but be safe

You probably don't have a paper gasket between the metal housing and the intake manifold. All you have is a rubber gasket around the thermostat rim. The new one may not even come with a replacement now that I think back. I reused the original--check the box when you get it.

Unburned what?

basically, what he is saying that it isnt hot enough, so some garbage my be buil;t up that would otherwise be burned off, i would suggest replacing yours with a 180* t-stat

Right. It'* calibrated to have the walls hotter. Running colder means unburned gasoline is on the walls diluting the oil there. A friend had a van that he drove to Cleveland and it always was cold inside because they couldn't get much heat out of the heater. Later the rings were worn and they junked the van. I suspect it had an open thermostat.

I'd rather have the car warmed up to the 195 that it was engineered for. I realize there're some who run at 180.

i still suggest going with the 180 t-stat, im starting to think this may be why my UIM and LIM and gaskets looked so good after nearly 120k miles. I have been running a 180* for three years now, since about 60k miles

where can i get that kind of t-stat and how much do they cost? Do you know the part number?

any parts store will have it.. under $10

and the only gasket that i will need is an oring off of the original?