[Cooksta3276]

Hi everyone, I'm glad to be here.
I have a '14 ECO manual, 90k miles. I replaced the thermostat about a year ago and she was running great til now. The temp guage barely moves on a 20 mile ride to work (yes these cars warm up slow, but not this slow) so heat is pathetic and we're down to the 20's and 30's overnight now. I'm getting a PO128 error after 10 minutes driving, failure to adequately warm up and the "AC off due to high engine temp" warning pops up and the guage goes ALL the way back to cold. I clear the code and the guage goes back up a hair. I'm also getting a P59F error "shutter actuator fault" and P69E "fuel pump pressure fault." The car runs fine so I know there's not a fuel problem. If the car sits and idles it will get up to full operating temperature eventually. I don't know why it'd be the thermostat, since even stuck open the car would eventually hit operating temp after 20-30 miles. Maybe the shutter is stuck open and cooling it down too much, but it was doing this when the outside temps were in the 60s and 70s. Any tips or help is greatly appreciated! I'd like to have heat and the ability to defrost the window before we start hitting consistent sub freezing temps.

 

[Johnny B]

Ok dude, calm yourself. You have let your car build up issues and now winter is coming, I get it.
You biggest problem is the thermostat, I believe you replaced it. But, I also am very confident it is now stuck open. Failure of a replacement thermostat after a year is actually pretty common depending on what replacement was used. I'd use either the OEM or Dorman thermostat this time.

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guage goes ALL the way back to cold. I clear the code and the guage goes back up a hair

The car DIC coolant temperature gauge only reads out the "actual" coolant temperature part of the time. It is programmed to read out feel good numbers so people don't obsess over every little change. For the real temperature you will need to monitor the ECT on a scan tool.

Maybe the shutter is stuck open and cooling it down too much

I agree the shutter is probably stuck open, but your cooling issue has nothing to do with the shutter being open. There are thousands of cars running just fine without a shutter at all.

And your fuel pressure fault is most likely the sensor, because if you actually have low fuel pressure the car wouldn't run. Take care of the thermostat first, then we can fix the other minor issues.