The only one I know of is on the passenger side I dont know what sensor is on the drivers side

 

When I bought my 2018 Z06 and was driving home from the dealer, I noticed it was running cooler than it should (around 165 degrees). The dealer told me that was "normal" on my car. When driving in cooler weather, the rpm redline on my tach would drop back indicating I shouldn't red-line my rpm due to the engine being cool (that occurs at anything below 163 degrees on my car).

I'd read that others had a similar problem and decided to change the thermostat because I was convinced it really was a cooler than specified temperature, by watching the oil temperatures etc. So, I ordered a new OEM thermostat and replaced it. I was surprised that the temperature ran at exactly the same temperature as the original thermostat that came new in the car.

I lived with that for quite a while, reading more posts by people on this forum who experienced a similar issue. So, I bought a non-oem thermostat from Rock Auto that actually described the thermostat as being a 190 degree thermostat. Last week I installed that thermostat (the 3rd one since I bought my car) and my temperature is perfect now.

On a cool morning, the temperature goes up to about 205 degrees (indicated), the oil temperature goes up appropriately and then as the system stabilizes it runs at about 195 degrees.

I've concluded the OEM thermostats (at least some of them), open too soon and don't allow your car to run at the design temperature. That's consistent with my experience, and of others I've read about on this forum. Apparently some of the OEM thermostats run at the proper temperature and some don't. An unusual problem and one I've never encountered previously.

I hope my experience helps some of you who may have experienced a similar problem.

 

Not sure if this means anything, but...
When I take our 2017 Z51 into a touchless automatic car wash, both the coolant and oil temps drop considerably from the water spray. Eventually they go back to normal but it takes several minutes.
Years ago the coolant thermostat on this car was not closing properly sometimes, both temps would occasionally drop by about 20' for no reason. I had the thermostat replaced and the "temps drop for no reason" problem disappeared, but I still get the big temp drops in the car wash.

 

"Glitches" can reset, as yours did; other things like faulty senders (which I've had on another Vette engine) don't. Drive it and see what happens. Like so many of these kinds of things you may never see it again, or maybe in the morning? No predictability. (btw, I had something similar on my new C5 back in the day, dealer could do nothing, hasn't happened since... just sayin')

 

I had this issue (analog coolant temp gauge at zero, fan running at high speed when engine turned off, and AC not working) on a recent trip to a car show. I was freaked out and watched by oil temp like a hawk until I got home.

After doing A LOT of research online and here on CF, I was pretty convinced it was due to the thermostat. I also found that the issue had temporarily(?) corrected itself, so I took a drive (Florida, high 80s) and noticed that my coolant temp never got above 175 degrees. All indications were that this was too cool and was the root cause for this issue occurring.

I bought a RockAuto OEM replacement thermostat w/ housing (https://www.rockauto.com/en/moreinfo...pt=2200&jsn=10) and installed it this weekend. Went for a long drive and the coolant temp leveled out at 195 degrees. Hopefully, no more issues!!

I went ahead and also changed the coolant temp sensor (2016 located on drivers side) while I was at it. The original one is probably fine, so I have a back-up now if ever needed.

 

The coolant temp sensor was in one location in earlier C7s, and was moved for later C7s. See below pic. The above pic is the oil pressure sensor (with the horizontal plug).

 

^^^^
That settles that

 

There are 3 reasons this can occur:

1. Bad ECC Sensor
2. Bad Thermostat
3. Bad Battery

If the code sets even in hot weather, its 1 or 2, but in cooler weather and if it sets intermittently its your battery. The sensor apparently can report "low" values when it has an abnormally high resistance (and thus a lower voltage).

It happened to me right before I put the car away. I idled it later in my garage, and checked the temp (sensor reports correct values) and to see if the thermostat was stuck open (it was not car warmed up when idling). So for me its replace my 7.5 year old battery in the spring and see if that fixes it.

 

First off big thanks to all of you who take your time out to share your experiences and advice. Its extremely helpful and appreciated.

I seem to be having a similar issue with my 2015 Z06. My issue is the warm up gauge on the tach that prevents redline shows the car being "cold" or still warming up after the engine temp reaches optimal running temps which are within range of 180-200. I just replace the thermostat n pump with OE replacement and the batter is maybe 3-4 yrs old and a diehard gold or platinum I believe. The warm up gauge shuts off when the car warms up and then comes back on after driving for 20 mins or so showing a completely cold engine. The AC also shuts off. Not sure what to do as this is extremely frustrating.

Any and all help is welcomed and appreciated. Thanks all.

 

Try replacing the temp sensor which is located near the thermostat. I had both replaced, thermostat and temp sensor, when I had the problem, Hope this helps

 

Mine was also a bad Tstat, but once I replaced the battery the code never set. I could just tell the car didn't warm up enough, I'm sure if I drove it in actual cold weather it would have set the code again.

 

My experience was that the cold eng light light, rev matching, air cond, and eng temp gauge all quit—and the cooling fan would activate when I shut off the engine. I went for a bit simply disconnecting the battery negative pole and the system would reset and all would be fine, but only for a short while. After replacing the temp sensor, it behaved for a while, but soon the problems resumed.
I replaced the thermostat some months ago and have had zero issues.

 

I just went through this.

I replaced the thrmostat, temp sensor, and disconnected the neg lead on the battery for an hour. No problems since the fix 3 weeks ago.

Notes:

1) Until you fix this, your fan will run for about 20 mins everytime you start the car.

2) The temp sensor is easy to replace and cost me around $14 at Autozone.

3) The thermostat is a bit awkard to remove and took me almost 30 mins due to frequent breaks in a hot Texas garage. Picked a new one up on Amazon for around $80.

4) Put down a drain pain to catch the coolant. I skipped this step and had to powerwash my garage and refill the coolant tank after.

 

Already did the thermostat yesterday thinking that was the cause (again) yet it didnt fix it. So I have a sensor coming and will replace that tomorrow. Once I install that ill do the battery disconnect to ensure it resets everything and go from there. Hope that works.

Thanks for your time to respond.

 

Just adding to the thread a few years later since I just had the problem and thanks for the replies on here it saved me money.
C7 2014 Z1, convertible, 43,000. Was driving and noticed the temp gauge was not working but all other indicators were fine, after about 30 minutes into the drive the check engine light game on. . ODB reader (handy and cheap on Amazon) said it was thermostat but after reading this thread I decided to try the cheapest and easiest solution first and change out the sensor with an AC delco for $40 at AutoZone. Install took about 30 minutes, lost very little fluid, basically what got released from pressure (maybe 2-3 ounces). My 2014 sensor was on the passenger side next to the thermostat and below the air intake which I removed to make it easier. After install I disconnected the battery to reset the error codes and because it’s a convertible had to reestablish (disconnecting battery disables the electric top) that by lowering both windows and raising them up again, quirky but it worked and my dashboard directed me to do it. I had planned to go to the dealer but they couldn’t see me for 4 days and likely would have replaced both the sensor and the thermostat out of caution and much more coolant leak. Cars running like a champ.

 

Wow. Lucky for you it may have been just the sensor. I actually just had the car serviced at a local dealership service center with a Z tech appx in Jan 2026. The temp gauge hadnt acted up recently but I was getting a constant CEL with P0171 (lean bank one) code (which in the end the tech believes was correlated to the temp gauge acting faulty.

The first attempt at a quick resolution they decided to try a coolant flush since I never did that after changing the thermostat twice. They thought it may have an air pocket that I didnt purge and that may be causing the issue. I agreed only because it was cheap enough ($290) and I figured it needed it at this time (42,000 mi) after all its been thru. I was skeptical that was gonna fix the issue tho.

Sure enough the CEL came back on a day after driving it. This time when I brought it back they did a thorough check with smoke test and it ended up being a bad intake gasket on the SC. Just my luck. Haha. It ended up costing me around $2,300 for the repair that of which the new seals only cost $190. All the extensive labor is what killed me. But im happy to know at least the SC is practically brand new with all new seals.

i cant say how its driving yet since I havent driven it since it was fixed. I live in NYC and the weather has been trash since then. Im fairly certain this was the root of the problem causing all my issues tho.