Weird coolant temperature issue
Thread Starter
Advanced
Joined: Oct 2009
Posts: 51
Likes: 3
From: Wichita Kansas
Weird coolant temperature issue
I have a '16 Z06 that has been giving me a weird issue for over a year. I will be driving along and the coolant temperature will lose its signal to the ECU. The gauge will no longer display a reading (shows the needle at the very beginning of the temp). In turn, it shuts off my A/C, turns the radiator fan on nonstop (even if you shut the car off) and makes it run is some kind of limp mode. Although, there usually is no CEL or code, I can clear codes with either of my diagnostic scanners and it will instantly fix the issue and everything will go back to normal. I don't have to pop the hood or touch anything else. I have replaced the coolant temperature sensor, but it did not fix the issue. If it was a wire or connector issue, I don't know how my scanner can instantly fix it. It may not happen again for a few drives, but it eventually comes back. Once the issue does occur, it will not clear or fix itself until I either disconnect the battery or clear the codes (which usually none are present, the only code that may come up is about the coolant temperature). What else is on this circuit that could be giving me this issue?
Safety Car
Joined: Feb 2002
Posts: 3,726
Likes: 368
From: Montoursville Pa
the usual suspects are a bad ground which tends to show up intermitantly after years of ownership, and or fretting corrosion in a connector usually fixed by simply removing and reconnecting the connector. (ecu maybe)
Last edited by ErnieN85; Nov 9, 2020 at 11:01 AM.
8th Gear
Joined: Oct 2020
Posts: 8
Likes: 3
From: Oklahoma City, OK
I have a '16 Z06 that has been giving me a weird issue for over a year. I will be driving along and the coolant temperature will lose its signal to the ECU. The gauge will no longer display a reading (shows the needle at the very beginning of the temp). In turn, it shuts off my A/C, turns the radiator fan on nonstop (even if you shut the car off) and makes it run is some kind of limp mode. Although, there usually is no CEL or code, I can clear codes with either of my diagnostic scanners and it will instantly fix the issue and everything will go back to normal. I don't have to pop the hood or touch anything else. I have replaced the coolant temperature sensor, but it did not fix the issue. If it was a wire or connector issue, I don't know how my scanner can instantly fix it. It may not happen again for a few drives, but it eventually comes back. Once the issue does occur, it will not clear or fix itself until I either disconnect the battery or clear the codes (which usually none are present, the only code that may come up is about the coolant temperature). What else is on this circuit that could be giving me this issue?
I have the very same EXACT problem on my '16 1LT...It is going to the dealer next week for transmission shudder and I will have this fixed as well hopefully.
Intermediate
Joined: Dec 2018
Posts: 29
Likes: 4
From: Northern Virginia
The symptoms you are describing are the same I had when the thermostat failed on my 2016 Z06. Cleared the code once because I was on a road trip far from home and things were normal for a short time and then reverted to the fans screaming and no AC. Replaced the thermostat which had a tear in it and all fixed.
Thread Starter
Advanced
Joined: Oct 2009
Posts: 51
Likes: 3
From: Wichita Kansas
It's not really running hot, it just thinks it is. As soon as I reset the ECU, it reads the coolant temp correctly. Would a tear in the thermostat seal be creating air pockets that mess up the sensor...I'm assuming? Is the ECU located in the rear close to the battery? I took a look a quite a few grounds, but they seemed tight.
Intermediate
Joined: Dec 2018
Posts: 29
Likes: 4
From: Northern Virginia
In my case it was below freezing outside and because the thermostat was torn it never got up to normal operating temperature and eventually the car set a P0128 coolant temp code. In doing a little research it appears because the computer realizes it is getting an out of range temp reading and doesn't know if it's too hot or too cold it turns on the fans to high speed and shuts off the AC to protect the engine in a worst case scenario. It took me 15 minutes to pop out the thermostat when I got home to validate the problem.
Instructor
Joined: Jan 2017
Posts: 133
Likes: 3
From: Lawton iowa
My '14 Z51 is doing the same thing. Temp gauge all the way down and not registering a temp at all. Not running hot but fan runs constant even when engine is shut off. Has done it twice. Both times I disconnected the battery for an hour, hooked it back up, and problem gone. Has not done it a third time yet. Maybe fixed itself.
8th Gear
Joined: Oct 2020
Posts: 8
Likes: 3
From: Oklahoma City, OK
Fixed!!!
Took the car to the dealer this past week and they were able to solve this mysterious problem. Found that the thermostat was stuck fully open. Removed and replaced thermostat and problem has gone away.
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