Thermostat Rationality CEL Code P0128
#1
01-03-2008, 11:37 AM
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Thermostat Rationality CEL Code P0128
My light tripped the other day on my '08 6.7 Mega 4x4 with 1500 miles and threw that code. The engine was warming to operating temp when it occurred. I just started using the engine block heater a day or so before this happened. Looking at how the computer "sees changes" I suspect there isn't anything wrong. The dealer reset CEL and said they were going to replace the thermostat when they get one in.
The attached patent information offers an explanation for how the system works.
Thermostat Rationality: [/align]A method is provided for testing a thermostat in a motor vehicle. The method includes an engine warm-up model and a thermostat diagnostic. The engine warm-up model predicts the temperature that the engine coolant temperature should be equal to at a given time after start-up. This is based on the engine coolant temperature at start-up, ambient air temperature, and how the vehicle is driven subsequent to start-up. This predicted engine coolant temperature is compared to the actual engine coolant temperature as read by an engine coolant temperature sensor. The error between the predicted engine coolant temperature and the actual engine coolant temperature is calculated and integrated over time. The thermostat diagnostic runs at a pre-selected temperature after start-up and compares the integrated error to a predetermined threshold value. Depending upon the results of the comparison, a pass, fail, or inconclusive condition is determined. [/align]
The attached patent information offers an explanation for how the system works.
Thermostat Rationality: [/align]A method is provided for testing a thermostat in a motor vehicle. The method includes an engine warm-up model and a thermostat diagnostic. The engine warm-up model predicts the temperature that the engine coolant temperature should be equal to at a given time after start-up. This is based on the engine coolant temperature at start-up, ambient air temperature, and how the vehicle is driven subsequent to start-up. This predicted engine coolant temperature is compared to the actual engine coolant temperature as read by an engine coolant temperature sensor. The error between the predicted engine coolant temperature and the actual engine coolant temperature is calculated and integrated over time. The thermostat diagnostic runs at a pre-selected temperature after start-up and compares the integrated error to a predetermined threshold value. Depending upon the results of the comparison, a pass, fail, or inconclusive condition is determined. [/align]
#3
01-21-2008, 09:43 PM
RE: Thermostat Rationality CEL Code P0128
Had the P0128 MIL this AM (Cooling System Error / Thermostat Rationality). I had the block heater plugged in all night as the temp was down to 14 degress and was 17 when started this AM. Warmed up for about 5 minutes before driving. Drove about 4 miles before light came on.
I had the G30 recall taken care of about 2 weeks ago.
I saw no temperature differences all day driving a total of 100 miles with 3 stop and starts.
Should this be ignored or have dealer check it out or is it just a cold weather issue?
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07 6.7L CTD Quad Auto 4x2
No mods/chips[/align]
I had the G30 recall taken care of about 2 weeks ago.
I saw no temperature differences all day driving a total of 100 miles with 3 stop and starts.
Should this be ignored or have dealer check it out or is it just a cold weather issue?
---------------------------------------------
07 6.7L CTD Quad Auto 4x2
No mods/chips[/align]
#4
01-21-2008, 10:39 PM
