Engine light came on, then went away...

Despite appearing to run fine, a dashboard engine light came on in my 2005 Jimmy. I tried the ol' tighten the gas cap trick, as well as disconnecting the battery, but no luck. So my garage ran a diagnostic and recommended changing the thermostat, but they couldn't remove the old thermostat due to a siezed bolt. I never did have them change the thermostat because ever since the garage cleared the codes, the engine light has never come back. Its been several weeks now, running fine, temp gauge indicates all is fine. Should I have the thermostat changed anyway and risk snapping a siezed bolt?

Strange that a 05 would have a stuck stat bolt.

What was the code no pulled?

So how much did they charge you to not change the thermostat?

Strange that a 05 would have a stuck stat bolt.

What was the code no pulled?

My invoice reads "Code P0128 Coolant Thermostat".
($53.68 CDN)

My invoice reads "Code P0128 Coolant Thermostat".
($53.68 CDN)


Code does not say replace stat just like a 02 sensor code does not say replace 02 sensor.

Code only say that the engine tempt is not warming up as fast as it should.
Could be weak stat or a bad pcm tempt sensor bad.
PROPER TESTING BEFORE THROWING PARTS AT IT.

On the stat bolt very unusual for one to be stuck on that new engine.
A good tech/mechanic may be able to get it out without twisting off.

Thanks MT.

It is strange that the bolt is stuck, considering that the previous owner had some warranty work done in '06 which included a new thermostat.

If I pursue this further it would be with another licensed mechanic that I know, but since the dashboard light has not returned, should I let sleeping dogs lie?

You are welcome.
I would watch it and see how it does.
Does engine and heater warm up like they should?
Clear codes and see if code returns.
Not all codes turn on check engine light.
Good luck