This sounds pretty typical of a 160 degree thermostat during the winter months in MO. It even happened to me one day in Florida when the ambient temps were in the 40s and I jumped on the highway right away. The car did not come up to temperature quickly enough, the engine temps dropped to 0 and the fan stayed on for 10 minutes after shutting down the car. The issue eventually resolved itself in the afternoon when the ambient temps were a bit higher and the car came up to operating temperatures quick enough. I'm not exactly sure what the proper temperature is but I think it's between 165 and 175. You can try to either replace the thermostat with a 175 minimum or stock 205/190. Or, you can have that ECU code tuned out so it never turns on. For what it's worth, I opted to leave it on in my tune and just be careful to not jump on the highway right away when it's cold out.

 

Strange business here: My car (‘14 M7 Z51) has continued to show these symptoms and I have been routinely detaching the ground battery cable to reset. I bought a thermostat, but do not think this is my problem.
Several days ago when driving through town (without rev match, A/C, engine temp gauge and radiator fan blowing) I happened to recall an entry I read in a Camaro Forum and switched my ride selector from Sport to Tour,—Voila!—the temp gauge came on. So of course I tried rev match and it worked too. Then I switched it back to Sport and they stayed on. The system seemed to re-set itself when the ride selector changed. No Battery cables needed.
I went into the controls and changed the suspension and steering to align with the ride selector, and it’s been several days and a hundred miles or so and it hasn’t failed again yet. I have turned off the engine sound control too. I’m wondering if having different steering and suspension settings might have triggered this. I’ll post again in a few days to let you know if this hack’s got any legs. It hasn’t gone this long without switching off for a couple of months. Stay tuned.
UPDATE: This post is a week later, 3/16, and after a couple hundred miles, Rev Match, engine temp gauge etc. are still operating normally. I think this is because I went into the controls and ‘synced’ the suspension and steering to be determined by the ride selector **** (I use ‘Sport’) on the console. Mine is a 2014—-I turned the exhaust sound management to ‘off’ a long time ago. The car has not gone this long without this occurrence since this started last October (or thereabouts).
2nd Update: Today is 4/21 and the problem has not re-occurred (daily driver). Again, the syncing of steering and susprnsion tpo the dash ride control **** seems to have done it.

 

UPDATE: 10/19/22 Pretty sure it was the thermostat. Gauge stayed pretty cool and then read hotter on warm days. After installing a 205 degree t-stat, the gauge now reads steady at just below 220 degrees. Put a couple hundred miles in the cooler fall weather and no issues so far. Took me a couple of hours to install after the helpful U-tube video. Damn parts guy made me buy the whole housing to get the t-stat—I took it out and just installed it by itself.

Yet another update: 4/30/23
Absolutely (see Bruno below) was the thermostat—many months and no further issues at all.

 

Glad you got it solved. Luckily it was a cheap easy replacement.

 

For anyone reading this thread. It’s virtually always the thermostat. Anyone trying anything before replacing the thermostat is wasting time and money.

I say this in every post about this. It comes up pretty often. People refuse to change the tstat first and think it’s all sorts of other issues.

the c7 causes numerous things to happen when it doesn’t warm up above 170 degrees in a normal amount of time:
ac stops works
Rev match stops working
temp gauge reads 0
fans full blast

you can reset it with a code reader then do it again.

 

BRAVO

It seems everyone wants to replace the coolant temp sensor. It's the thermostat people. And, it's not just a bad thermostat causing these symptoms, a lower temp thermostat can cause these issues even when working correctly.

You can't throw a lower temp thermostat in the car and expect it to run as stock. You will have issues, some of which you can tune out.

 

Bruno and 6Speeder made me a believer.

 

winners winners chicken dinners. In my 2016 Z06 with 18K miles, I was getting 0 coolant temp, no rev match, fans ON after shutoff, and, a pending P0128 CEL. I put the car on a flatbed to get it to a dealership for a thermostat replacement. Very lucky for me... the car battery wouldn't start the car once at the dealership. So... I instead replaced the battery, and the car has been WAD (working-as-designed) since. This was 3 months ago.

My original battery lasted 41 months. The 2nd battery lasted 36 months. I don't use any trickle charger.

 

There is only an engine coolant temperature sensor and an engine oil temperature sensor. In your picture, the digital engine temp is a higher resolution display of engine coolant temp than the analog display in the lower right corner. I have a Z06 and do not have an analog engine temperature display as that lower right display location is used for the boost gauge. I never pay attention to the analog displays due to their poor resolution.

Bill

 

CORRECTION: I had the same 0 coolant temp, no rev match, fans ON after shutoff, and, a pending P0128 CEL issue occur again recently. I disconnected the battery for 30 mins, then re-connected it, and, everything is working again. Apparently, the timing of this, and a failing battery was just a crazy councioucidence.

 

If (when) this next occurs, drive it home and replace the thermostat. That it will permanently fix it. 20 minute job at home in your garage.

 

If you replace the thermostat, do you also need to bleed the coolant system? I've heard estimates that replacing the thermostat will lose approx 12 ounces of coolant.

 

I got a pan to catch any drips and put shop towels beneath the t’stat—that turned out to be over-prepared. Made sure the engine was completely cooled—lost a fewoz of fluid. Didn’t completely soak a blue paper shop towel. I don’t know if others had the same experience, so YMMV.

 

The 0* coolant temp is what doesn't make sense. If it was a bad thermostat it wouldn't indicate 0*.

 

The computer controls what the gauge displays, it is not a direct connection from the sensor to the gauge. A failed thermostat, one that is stuck open or opening too soon can cause the ECM to trigger the cooling fail-safe mode. What happens is that the ECM expects that after so many minutes of operation that the coolant temperature will be at or above a certain temperature that correlates with the thermostat opening temp. If the ECM does not see that the temperature has warmed up, it knows that something is wrong, and one possibility that the programming takes in to account is that the coolant temperature is not being reported correctly. The ECM will then enable the overheated engine cooling mode to be on the safe side. This forces the radiator fan on full speed, disables the AC and rev-matching and when the vehicle is shut off, the cooling fan will continue to run for several minutes at a reduced fan speed, even if the engine is not overheating. Code P0128 may be set as well.

The first instance of this being observed, it will not cause the check engine light to illuminate, but the water temperature gauge will drop to 100, the fans will go to full speed, the tachometer engine cold “yellow halo” will be present, and you will lose rev matching. On repeated drive cycles where this is observed, the symptoms remain the same and the check engine light will be on as well.

Yes, a failed temperature sensor can cause this, but in most cases, the real culprit is the thermostat, it is opening too soon, or is not closing fully when the water temperature is below the thermostats operating temperature, causing the engine coolant temperature to rise too slowly and not reach the minimum expected temperature. Obviously, cooler weather tends to expose this issue. Installing a cooler temperature thermostat can also cause this issue.

The difference between actual overheated vs. this failsafe mode is that the temperature gauge will read 100 even when the temperature of the coolant is above 100 degrees. If the engine was actually overheating, the temperature gauge would show the high temp. Note that you can check the engine oil temperature and see that the engine is not overheating. This is also agood check for a stuck open or early opening thermostat as well, if after several minutes of operation, the oil temperature is well below 200 degrees, the thermostat is most likely the cause. In my case, the original thermostat failed after 107K miles and 7 years of operation. Fortunately, it failed this way as opposed to stuck closed.

Once the vehicle is fixed, if the code is not cleared, the temperature gauge will not move off 100 and the cooling fan will be on at full speed until the engine coolant temperature reaches the expected warm engine temperature, then the gauge will reflect the correct temperature and the fan will return to normal operation. Both the thermostat setpoint as well as the overheated engine fan run time and speed after vehicle shutoff are values that can be modified with a tune.

 

This is exactly what happed to me yesterday. 2014, auto, 68k miles.
I noticed my temp gage was stuck on 100 after 5 miles of freeway driving. Radiator and hoses were cold. Engine ran well and did not smell hot. The overflow tank was at level and cold.
The local parts store had a new 207 deg stat in stock, so I swapped it out in about 1/2 hr, added a cup? of water and started it up. Temperature gage started moving quickly.
207 deg seems like a odd ball #, but the stock is 194? The temp gage shows about 220. I haven't checked the actual temp.

 

You did good. The 207* thermostat is the correct one for the 2014. I have researched a lot,,,, and can't find why the later years are 194*. On later years the temp sensor is in a different location. I have a 2014 with a new 207* thermostat and it runs perfect at 220* coolant temp. Not to worry.

 

Why is it always the thermostat instead of the temp sensor?

Well, the temp sensor is electrical and consists of only one part, a thermistor, which are extremely reliable and very rarely fails.

On the other hand the thermostat is mechanical with many parts thats always moving, opening and closing. Thus a higher failure rate part compared to the temp sensor.

When the thermostat fails every thing goes 'wacky', and most people can't believe it is just simply the thermostat. Makes one think there is a very serious problem with all the systems but that is just how the computers software works.

 

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