Heating issue
Drifting
Joined: Dec 2019
Posts: 1,817
Likes: 616
From: Blacksburg Va
Over many years and many cars this is the first time I have ever seen a car where engine temp is different than coolant temp. Do those come from different sensors, one in the engine and one in the coolant? Or are these actually the same temp from the same sensor that are labelled differently on the different displays? I see in the picture in post 12 that the digital and the analog are at about the same of 199deg. What is the analog gauge labeled as? I was going to look at mine but it is a 2019 so wouldn't necessarily the same as a 2014.
Le Mans Master
Joined: Jun 2019
Posts: 5,520
Likes: 2,206
From: Loveland
Only the 2014 have different, Engine and Coolant temps. The later years they are the same. I think it was an engineering thing on the 2014. Someone thought it would be a good idea to make the engine temp different. There isn't a different sensor, but the reading coming from the sensor, goes through the ECU, then to the two readings. I unhooked the sensor wire and both temp readings went blank. There is a different oil temp sensor, of course.
Melting Slicks
Joined: Oct 2022
Posts: 2,839
Likes: 2,383
From: Phoenix, Arizona
2025 C7 of the Year Finalist- Unmodified
2024 C7 of the Year Finalist - Unmodified
Only the 2014 have different, Engine and Coolant temps. The later years they are the same. I think it was an engineering thing on the 2014. Someone thought it would be a good idea to make the engine temp different. There isn't a different sensor, but the reading coming from the sensor, goes through the ECU, then to the two readings. I unhooked the sensor wire and both temp readings went blank. There is a different oil temp sensor, of course.
Melting Slicks
Joined: Oct 2022
Posts: 2,839
Likes: 2,383
From: Phoenix, Arizona
2025 C7 of the Year Finalist- Unmodified
2024 C7 of the Year Finalist - Unmodified
Thread Starter
Melting Slicks
Joined: Jan 2017
Posts: 2,707
Likes: 897
From: CONCORD CA.
The reading of the analog gauge is 220° (not 200°), vs 199° on the digital one. I know that the ECT supplies a reading to the analog gauge (I disconnected it once, and had no reading was displayed on analog gauge). I've seen people post that the analog gauge reads engine temp (not coolant temp). I'm still having a hard with this in that, no other gauges give a reading anything near 220° (coolant or oil).
Pro
Joined: May 2022
Posts: 575
Likes: 245
From: Peoria, Arizona
This has been discussed many times. I has been agreed upon, I think, that the 2014 analog gauge is a general "I'm working gauge". It isn't exact at all. Most everyone with a 2014 has it sitting about 220. The disagreement is with the digital gauge. My digital reading will go up to 206ish, then immediately drop. This cycle slowly repeats as the thermostat does it's job. This means it's reading my COOLANT. Therefore, I say it's showing me my coolant temp. Why they labeled it "Engine" temp, nobody knows and unless we get an original GM engineer on her to tell us the facts, we will never know. And as was posted here, the sensor is embedded in the coolant flow. According to kodpkd, this sensor is for both the analog and digital gauges. That must mean that the ECU is programmed to give a "general" output to the analog compared to the digital. By default, that logically means the car engineers meant for the digital gauge to be the reliable reading of the COOLANT. At any rate and regardless of what is correct, those with a 2014 have only one source to look at for coolant temp, and that is the digital gauge. There is no other gauge.
I also think it was your t-stat. Trapped air would have had an immediate effect.
I also think it was your t-stat. Trapped air would have had an immediate effect.
Thread Starter
Melting Slicks
Joined: Jan 2017
Posts: 2,707
Likes: 897
From: CONCORD CA.
This has been discussed many times. I has been agreed upon, I think, that the 2014 analog gauge is a general "I'm working gauge". It isn't exact at all. Most everyone with a 2014 has it sitting about 220. The disagreement is with the digital gauge. My digital reading will go up to 206ish, then immediately drop. This cycle slowly repeats as the thermostat does it's job. This means it's reading my COOLANT. Therefore, I say it's showing me my coolant temp. Why they labeled it "Engine" temp, nobody knows and unless we get an original GM engineer on her to tell us the facts, we will never know. And as was posted here, the sensor is embedded in the coolant flow. According to kodpkd, this sensor is for both the analog and digital gauges. That must mean that the ECU is programmed to give a "general" output to the analog compared to the digital. By default, that logically means the car engineers meant for the digital gauge to be the reliable reading of the COOLANT. At any rate and regardless of what is correct, those with a 2014 have only one source to look at for coolant temp, and that is the digital gauge. There is no other gauge.
I also think it was your t-stat. Trapped air would have had an immediate effect.
I also think it was your t-stat. Trapped air would have had an immediate effect.
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Le Mans Master
Joined: Jun 2019
Posts: 5,520
Likes: 2,206
From: Loveland
I purchased a laser thermometer. I tested the thermostat housing as it was warming up, when the coolant gauge was below the magic 220*. As the temp got to 220* I tested the housing again, it was a bit below 220*, went for a drive, Tested again, it was still just a bit below 220*, drove it a little harder and checked again, it was still just a bit under 220*.
Pro
Joined: May 2022
Posts: 575
Likes: 245
From: Peoria, Arizona
Thank you so much for the bulletin. I will say my temps never converge, but oh well. NOW we can finally put to rest what the digital gauge is reading. As GM says in its own bulletin, the gauge is called the "digital engine COOLANT temperature gauge". The digital gauge IS the coolant temperature, not some vague "engine" temp.
CGLADISH...stats can go bad in a few months. I've had one be bad out of the box. Most of the time we get good ones, but yours going bad after 10 months isn't unheard of.
CGLADISH...stats can go bad in a few months. I've had one be bad out of the box. Most of the time we get good ones, but yours going bad after 10 months isn't unheard of.
Thread Starter
Melting Slicks
Joined: Jan 2017
Posts: 2,707
Likes: 897
From: CONCORD CA.
Thread Starter
Melting Slicks
Joined: Jan 2017
Posts: 2,707
Likes: 897
From: CONCORD CA.
I understand something going bad prematurely, it's just when it happens several times relatively close, is when I'm a little surprised. As I mentioned already, this is the first time in 46 years for driving that I've had a thermostat got (let alone 2 in 10 months). Has the quality gone down that much or, it is a C7 issue?