About a month ago,I noticed the coolant temp gauge was down to zero. It did come back on the next time I started the car.
After reading up in this forum,I changed the thermostat. Problem solved. Until today,3 weeks later...the check engine light comes on...
and the gauge is zero,AGAIN...Drove it around all day,and stayed at zero.

So,is it a bad thermostat (which was brand new btw) or the sensor?

 

Did you use the ACDelco 131-158 GM P/N 12622410 ?

 

X2, anything but and this happens!

 

X3 plus what code number did it show this time ?

 

No,one from Pep Boys.

 

So that means ANY aftermarket t-stat except ACDelco won't work?
Kinda pisses me off...

 

Let me add when I took the old one off,the old gasket was fine,not deteriorated. I used the new one anyway.

 

Hmmm. The other 2 helpers got replies. I ask about the all important code number and get no response.
Hope you figure it out. I'm done.

 

It’s been mentioned many times here, the aftermarket t-stats do not open in the time frame the computer is calibrated for , the the code gets thrown. Most likely P0128.
And only use Dexcool 50/50 mix, these Ecotec engines were engineered for it.

 

The paperwork from Autozone with the code is out in the car,which is NOT home right now,so I couldn't reply.
Jeez,NO patience.