Searched the forum and couldn't find an answer to this one. My 2007 Silverado 4wd 4.3 v6 threw a DTC today- P0128- Coolant Temp Below Thermostat Regulating Temp. Outside temp was about 55 degrees, and the engine coolant temp gauge showed the temp at about 185 where it usually reads. Heater was working okay. I'm guessing there is a sensor somewhere to go bad? Is this something I can drive with until Monday? Thanks.

 

Might be a bad tstat although i can't imagine why it would be bad on a 2007.

 

Yeah, the t-stat is definitely a possibility although the temp gauge seems to be in moving up to where it should. Thanks.

 

needs a new thermostat..a 195 degree

 

Thanks, I'll give that a try, although the code hasn't come back yet, and the outside temp was about 28 degrees yesterday morning.

 

I got the same code man...I've been looking for the problem solve for couple days. What did you do to fix your truck from that code poping up again? did you finally just replace T-stat??

Please reply with sum helpful hints. Thank you all for the help!

 

Take your T stat off, get a boiling pot, a candy thermometer, put the T stat in the pot, add some water and turn up the heat. When a T stat is marked 195, it means it should close at 195, not open. So therefore it should open at about 205. Then shut off the heat and let the temp go down to see what it closes at. This is an easy test to rule out a bad T stat.

 

okay budd..ill try that ..thanks alot ..you know its weird..My check engine light was off today when i climbed into the truck..started it..it was off...i live in South Carolina so it doesn't get to cold here. but ...It hasn't come back on yet so..I dunno what caused it to show up then DISSAPPEAR!!! ..wth..I dunno man some kinda freak of nature truck....ever heard of somthing like that?? also my temp of my truck doesn't climb pass 185. thats it..it stops no matter how long i have it running or how long i use it..it doesn't go passed...so I have no CLUUE!

 

Had the same problem at about 38000 miles. Changed thermostat & haven't seen that code since.