ive had this code twice now, the first time it popped up it went away by itself. It didnt show up for another year and sure enough almost exactly a year from then i get the same code.

I cleared the code with the Tech II we'll see if it comes back, but being this is the second time ive had it im thinking im going to fix it for good.

For those that dont really know what this code is. here you go//

Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

Ive looked around and it doesnt look like this code is very popular in the cobalt community.

What do you guys think? Im pretty much thinking the thermostat is faulty and is prob sticking open.

My cars coolant usually runs anywhere from 170-185 it WILL reach up to 200 VERY rarely and only for a moment. Looking at the tech II scanner it seams my car is running rich and according to all data normal coolant temperature is around 185-200 which my car is usually under.

So cliff notes

1: CEL P0128
2: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
3: car usually runs 170-185
4: I think my car runs too rich and too cool
5: Faulty Thermostat? Get new one?

Any input will help, thank you all

 

I got that code not too long ago on mine actually. Admittedly I didn't try to pinpoint whether it was the thermostat or the temp sensor. Got both at Advance Auto Parts (about 50 for both if I recall correctly) and about 20 minutes of my time and the code went away.

 

You got the IAT Sensor as well?

What was your coolant usually running at? What is it running at now?

Oh an thank you

 

I got the new thermostat and the coolant temp sensor that is at the backside of the block. My car from day one has run around 200 getting as high as 218 when the fan kicks on. As for what it was running at the time, I honestly can't tell you...when the code came on the DIC temp reading went to ---

 

Alright bud thanks for the info, ill prob just change both of em out also, 50 bucks isnt bad at all

 

not a problem man. if you have any more questions about it keep the thread going or just shoot me a pm...one thing I just noticed reading your sig is you're a TC so parts prices for yours might be a little bit higher than mine.

 

Yeah we'll soon find out =)

 

sounds good man...let me know how you make out with it

 

I have a TC... im not sure if your SC or not... but my car, in the summer, runs at about 190-195.. now that its cold out, i'm getting a steady 203... seems weired that its hotter in the cold, but its not throwing CEL, still runs great, and is always that warm.. so i'm not too worried