Coolant Temperature Sensor
 

I've recently replaced my Coolant Temperature Sensor, it starts out working and then when it gets warmed up it fails. There is a caveat here though this only happens when the outside air temperature is cold, when it's warm it seems to work fine, any ideas?

Burp your coolant!

Please describe the symptoms, what do you mean by fails? Why did you replace the sensor?

If you have -- on the digital coolant temperature on the dashboard, it almost always is a bad thermostat, not a bad sensor.

Intermittent sensor
 

First post in a bit, so bear with me... For some reason over the past three weeks my temp sensor has been going in and out. It'll read when I start then stop and go blank on the digital and drop on the analog, then start working again. Like I said, intermittent. Then last week it threw a code for the sensor. Cleared the code and it hasn't returned, but it has gone out three times since the cleared code but hasn't thrown the CEL yet???? Could it actually the sensor or something else??? It's got me scratching my head. Any advice would be greatly appreciated. Thanks.

Don’t know what it could be, what was the code?? Could it have been P0128?
That indicates the thermostat isn’t working correctly, replace the thermostat with an AC Delco 131-158 180F degrees unit.

Yes it is the P0128 DTC. It came on right after I filled my gas tank up this morning. I spoke with some of my more seniored co-workers and Google. I was told to start with the sensor, check both upper and lower hoses for deterioration to see if any of that could be the culprit. If the new sensor does not fix it, I'll bite the bullet and fork out a ridiculous amount of money for a new thermostat. Just wondering, why the heck is the thermostat so expensive??? $30-50 seems awfully high for one. I see the dorman and car quest and others being in the "normal" range but the AC Delco that I am seeing just about everyone here saying to use is like $50 bucks.

I’ve tested the rest and they don’t open up in the time frame the computer is looking for. That sets the code P0128. I’ve installed one in my 2011 2.4 way back in 2019, at 128,000 miles it’s still in there at 236,000 .
it’s paid for itself by working correctly
in my 2007 2.2 , I installed at approximately 90,000 miles and drove it till I sold it at 386,000 miles.
I don’t remember any Stant or Gates or motorad thermostats lasting that long in my driving days since 1970.

Same here, My temp gauge quit reading and my A/C quit working (middle of summer) I replaced the temp sensor. checked wiring, and finaly put in a thermostat (which I didn't figure made sense) Quite common for the thermostat gasket to come loose and stick the thermostat open just a bit, causing the engine temp to take just aa bit too long to warm up, tripping the error code p0128 and all the problems you are seeing is to tell you to change the thermostat. The aftermarket ones don't last and you will end up spending the extra $$ on a Delco unit. The darn thing will last 10 times longer. Also keep in mind the "permanent antifreeze" is only good for 5 years and should be replaced.

Thank you for the information. It just threw me off that all of a sudden the digital and analog gauges just stopped reading. So my first thought was the sensor, but I wanted some extra input. Then it threw the code and sealed the deal. Going to start with the sensor then the thermostat, then a complete flush and fill. Looking forward to that project.
Thanks again, and I'll be posting updates as projects progress. Got some good ones on the horizon.