Did the GM one have the big rubber inner gasket? The one that came on my 2011 looks like there is no inner gasket, but upon closer inspection, maybe there is a thin one. That is at the valve, not the housing.

I guess I'll just ask in here... my DIC has been showing, for a few months now, that my coolant will spike up to 210-215 after getting off the freeway. My dash, though, starts off at flatline but doesn't move past the 45% mark. I get no CEL for this. The fan does kick on at around 210, cools it off immediately, but then temp begins to climb again after that. I do have to check and add coolant every couple months, not a ton, but the reservoir slowly goes empty (I check after it has been running) so I put some in. However, when I top it off the coolant issue doesn't go away. Does this sound like the thermostat? The two different readings being so off? Thx for your time. :)

You may want to get the codes check anyway. There will sometimes be a code in the system with out a light.

If you have not had the thermostat changed it would be a good place to start.

However the fact that you keep adding coolant suggests your having a coolant leak like a head gasket or an external leak that is small to the point you don't see it under the car.

x2 what Lucky said.

And the analog gauge is nowhere near as accurate as the DIC temp display - the analog one seems to only show big swings in temp. Going by the DIC temp display as you have been doing is the most accurate.

Thanks for the responses! :D

I just had the car in for a check engine light a few weeks ago and no code showed up then when they did a diagnostic. I am assuming it should have shown up then if it was? This has been an issue for months so if it was pinging a code it may have set off then.

whopper- I have had some issues with finding small leaks, but they are just that, very small. Maybe I need to trace it. I think I may do the thermostat just to see, seeing as folks have reported issues. What symptoms would my car show for the head gasket? My gas mileage is still good, my oil level is good too and I haven't noticed a rough idle or anything.

Thx again!

Today I found another place to worry about! The plug on the t-stat housing (for the non-existent oil cooler) has a pin hole in it!!!!!!

" just had the car in for a check engine light a few weeks ago and no code showed up then when they did a diagnostic. I am assuming it should have shown up then if it was? This has been an issue for months so if it was pinging a code it may have set off then."

WHAT? if the CEL was on there had to be codes.

I should have clarified- no codes for the thermostat. I had two EVAC codes that I could not figure out, but the issue was the evap canister n cable. That was it.

Just had my CEL come on today and a code reader (Torque app on Android via ODB Bluetooth) tells me it's P0128. Analog gauge and DIC are both flatlined for temp. App showed me a reading of around 170°F (after 5 minutes of driving) -- must be from a different sensor?

Question for those who have been through this: Does it sound like a bad thermostat? Based on what I read here, that's the fix, but I wanted a bit of confirmation before I start tearing into my daily driver. (Not worried about doing the work; just have extremely little free time at the moment so can't afford to waste it fixing things that ain't broke.) Car ran fine and seemed to be warming up just fine, so I'm wondering about the possibility of a bad sensor instead. Roughly 60K miles on the car, give or take.

T-stat is stuck open. 192 F is normal. I bet your A/C doesn't work.