When you cold start the tractor and let it run for awhile does the temp gauge go up to the top of the scale then does it come back down ?
Sounds like the reason the sensor it throwing the code is because when it's hot the voltage drops causing the code F450 which I believe is the way it should work. You sure the sensor doesn't control the temp gauge also.
No, it doesn't return as long as the engine is running. When started from cold, It takes a few minutes for the temperature on the gauge to begin to rise, but once it does, it stays up there.
The more I think about it, the more I agree with your initial thought that it is simply a defective thermostat. It's the simplest explanation and would explain everything I'm seeing as well as meaning that both the sensor, temp gauge, and alarm are all doing their job just as they should. To support that, I just went out and started it (it has always been an instant starter) and saw that the temperature gauge was at full cold just as it should be after sitting all night. And the "check engine code" light was on.... again, just as it should be.
So if it is the thermostat, I think what fooled me initially was that for months now it hasn't happened by occassionally. and also the few times it did happen iI was just moving the machine around the yard so it never got so hot that it steamed or even heated the water in the radiator substantially - like what happens via the lower hose when an engine really heats up. I've just been purely lucky.
The only time I missed the alarm was for less than a minute and was because I was wearing the noise-canceling headphones. Good headphones, but one of the things they cancel real well is alarms.
I feel confident enough that I'll pick up a thermostat tomorrow at JD. Someday I'll get a workshop manual, too.
Got a few days, raining now & two days of snow forecast.
thanks,
rScotty - "its better to be lucky than smart"
