I have gotten all of these errors relayed to coolant. Typically I clear them and they don’t come again during that drive or until after the vehicle has been stopped a while.

P0128-00 (AA) Coolant thermostat (coolant temperature below thermostat regulating temperature)

P0116-24 (36) Engine coolant temperature - circuit range/performance - General signal failure - signal stays high

P0128-00 (74) Coolant thermostat (coolant temperature below thermostat regulating temperature)

The gauge will go down to zero or very low at times. Whatever happens seems to completely correct itself after the truck warms up. Like last night, after I cleared the error with the gap tool, the gauge went to dead center. I had been driving about 15 minutes.

I have replaced the thermostat and ECT with OEM parts. I have NOT replaced the housing.

What do you guys think? I guess I will try bleeding AGAIN. I have done it several times. If there is coolant loss, I can’t tell it.

 

Definitely sounds as though you have a sticking thermostat. Double check nothing has gotten stuck in the new thermostat. You can also boil a pot of water and see if the thermostat opens quickly and smoothly when immersed in the pot

 

Thermostat or Coolant sensor.

 

both have recently been replaced though. And both OEM.

 

Did you replace them because of these codes? or did you get these codes after the replacement?

Really does sound like a sticking thermostat, I doubt it would be the housing if it is not leaking.

when is the last time you flushed your system and changed the fluid, thinking a clog of some sort.

try to get the front of the truck up (like up a steep hill if you can or jack up), warm up the truck and open the bleeder and see if you are getting air out.

 

You need to verify operating temperature. All you faults are based only on the temperature sensor and the computer assuming the t-stat is stuck, etc. I bet you have a damaged sensor wire.