P0128 but I can’t figure it out!

[Big bubba]

About a month ago my check engine light came on. I checked and it came back at p0128. My temperatures looked to be good, heat is still hot. So I turned the light off. About 10 days later it popped up again. So I turned it off and it’s now popped up for the 3rd time. Any ideas on what I should do? I know it’s a code for a thermostat but I don’t see the point of changing out something that appears to be working? Open to suggestions!

 

[maple09pj]

Hey there, wondering if you figured out your issue. I'm not much help but I have the same issue on my 2016, sometimes get P0128 and also sometimes get P01289. Truck seems to run fine and temp on gauge is normal. I changed the coolant temp sensor and the problem did not go away.

 

[Big bubba]

Hey there, wondering if you figured out your issue. I'm not much help but I have the same issue on my 2016, sometimes get P0128 and also sometimes get P01289. Truck seems to run fine and temp on gauge is normal. I changed the coolant temp sensor and the problem did not go away.

I couldn’t find my previous log in information so I made a new account. I changed the thermostat and it hasn’t been on for 500 miles now.

 

[maple09pj]

Hey thanks for logging back in and giving me that update. After seeing this I watched my coolant temps a little closer and mine was running a little low 80-85c. Changed the thermostat and it’s running 90-93c and no more CEL.

For anyone else doing the job make sure you have a 1/4” universal joint or wobble extension for your ratchet. The one bolt is at a bad angle. Tape your 8mm socket to the extension so you don’t lose it into the abyss. Undo the metal fuel line that’s in the way and it gives you a little room. No fuel will come out. Especially helpful when you’re reinstalling that bolt so you don’t cross thread.
Cheers!