Temps have been way below normal here the past few days, (low-mid 40's). Yesterday I hopped off the highway after a 30 minute drive at around 70 mph.
A mile or so later, the MIL/Check Engine light came on. No noticeable drivability issues, but the coolant temp gauge was well below where it normally runs, (indicated halfway between the 160 & 210 marks, usually closer to the 210*).
I drove the 3 miles further to home, pulled the codes, and it had thrown a P01F0 3 times, (Coolant Temp Sensor). Coolant level is fine.
So here is my question - Does the sensor drive the temp gauge on the dash? Or does it only feed the temp to the PCM, and the gauge have a separate sensor circuit? Just trying to figure out if the sensor is truly bad, or could that sensor output just be a symptom of something causing low coolant temperature, (like a thermostat stuck open)? Anybody have knowledge or experience to share on this one?
Thanks in advance for any advice!

there one. the gauge will read 20-60* more than actual engine temp as well.....Mine is 40-60 off.....

Thanks Mark, yeah, I have always used factory gauges as more of a basic indicator, I doubt any of them are very accurate.
So the coolant temp itself could be fine, just a bad sensor? I don't know where it is located on the engine, hopefully an easy swap. And it is not an expensive part.

That codes leans more to stuck open thermostats than it does a faulty sensor. Your symptoms sound a lot like thermostats too.

quote:

P01F0

013 Silverado 2500 HD 6.6
2014 Silverado 2500 HD 6.6
Customer Concern: Code P01F0.
Average Reported Mileage: 0
Tests/Procedures: 1. Measure the actual engine coolant temperature.

2. Compare the value to the parameter in Engine Control Module (ECM) data on the scan tool. They should match within a few degrees.

3. If they match, see if the engine coolant temperature is dropping below 160 Fahrenheit.

4. If it is, check for the engine coolant thermostats to be sticking open.

Where would be the best location to check the actual coolant temperature? Is there a test port somewhere, or is there a good place to put my temperature probe a somewhere on the outside of the engine that would give me a close representation of the actual coolant temp that is passing over the sensor?
Thanks guys.

quote:

...is there a good place to put my temperature probe a somewhere on the outside of the engine that would give me a close representation of the actual coolant temp that is passing over the sensor?

Just thinking out loud here, but wherever the temp. sensor is located, once the engine is heat soaked, a contact probe next to, or in contact with, this sensor should give a close representation of the coolant temp on the inside of the jacket.

Use a non contact thermal temp gun.

They work well.

Aim it at anything you like and it reads the temp it sees.

I’ve used one many times to help diagnose engine issues.

You can point one right at the area around the temp sensor and rad hoses.

Thanks for all the good advice, Guys.
Ambient temps were back close to normal when I got back to this. External temp checks after 20-25 minutes of operation seemed to indicate fairly normal, (168-181* depending on locations). Gauge readings also seemed about back to normal.
Yesterday I drove it, and the MIL/CEL indicator had turned off. Truck is a late 2015 year model, built in August 5 years ago, and has 112K on it, so I will soon drain & flush it, then fill with new coolant, and look for any irregular stuff in the liquid that comes out of it. Hard to imagine a thermostat failing, then fixing itself, so it almost seems like something caused it to stick in a part-open position, and somehow cleared. I don't often see any solid impurities in factory coolant fills either, so I am kind of puzzled by this one...

Jim,
I run into the same issues on the big trucks with the coolant sensors. Especially running the orange or pink coolant. Erratic readings showing fault code of coolant sensor failure. Some times it is the sensor 5Volt reference. Low/high. Other times where as i pulled the sensor out of the coolant tank and cleaned off the probe.Slight accumulation
of slime on the sensor. Cleared the active fault and send it. I have never had to clean one where as the unit was running the regular green coolant. Most newer stuff has the Pink/Orange or red/yellow type.JMO....

I just replaced the thermostats in my 2012 LML Duramax. Fixed. Took about 45 minutes total.

My temps were semi erratic prior to changing them and I got the MIL, also. They stick open just as any other t-stat would...