PO128/P128

[gmtrailblazer]

To start, I SEARCHED, and could not find anything on these codes.
A couple of weeks ago, engine light came on (got scanned and code was PO128, filled with more coolant, then the light went off). Now today the light turns on again, scanned and they said it was P128/thermostat. My question is, are PO128, and P128 the same, should adding more coolant turn it off again, and does the thermostat need replacing?
Thanks!

 

[The_Roadie]

Thanks for searching, but the secret is that the second character is a zero, not a capital "O". Search for "P0128" and you'll see MANY discussions about changing the thermostat, which is the cause of 95%+ of these error codes.

 

[gmtrailblazer]

so for the thermostat, would this one fit?

Buy Stant Thermostat, 190 Degrees Fahrenheit 14659 at Advance Auto Parts

 

[tricguy007]

Yup that's the one u need

 

[Wooluf1952]

so for the thermostat, would this one fit?

Buy Stant Thermostat, 190 Degrees Fahrenheit 14659 at Advance Auto Parts

IIRC, that t-stat is rated at 86c (it's stamped on the bottom), that's only 186.8f.

I'm not sure if it makes a difference, but you might want to check the specs on the AC Delco OEM t-stat.

I think we had this discussion on the OS.

 

[The_Roadie]

I don't think anybody sells unsuitable thermostats for the I6. They're all close enough. 185-190. Close enough for government work.