[Bauerlein]

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Here is a picture of the sensor, the thermostat assembly and the location of both the thermostat housing and sensor located right beside the housing. it it kinda hidden under the intake on the passenger side. The thermostat house runs from the passenger side to the drivers side and then 90's and head toward the radiator and attaches to the upper radiator hose. Maybe if you can find the upper radiator hose and follow it, you can fin where the thermostat housing is, and the sensor is literally about 1 inch from it..

Also, i guess i should add, i have a 2017 Acadia Denali, and apparently there are two different motors in that year, depending on which one you have, the other engine that is different than the one I have, the sensor is located in the front of the motor down low.

 

[JayTee2019]

Also, i guess i should add, i have a 2017 Acadia Denali, and apparently there are two different motors in that year, depending on which one you have, the other engine that is different than the one I have, the sensor is located in the front of the motor down low.

So . . are you saying that you have a 2017 Acadia Denali "Limited" Old Body Style? . . . It has the battery mounted below the floor in the rear of the vehicle.
Or do you have the newer smaller Acadia where the battery is under the hood with the engine.?

They made botht he older style Acadia and newer sytle in 2017. The older style was called the Limited. .. . look that up on the internet and maybe include that in your fourm signature with the "Denali" you now have there..

 

[speleos]

The 2017 Limited is NOT a Denali. The two shouldn't be confused. The Limited is an SLT-based Lambda platform Acadia.

 

[JayTee2019]

Of course and understood.
It may be confusing to some including the OP. He just mentions "two engines".
Regardless some such as OP may not know about the Lambda vs C1xx platform change.
At any rate. . if the battery is below the rear floor. . . that would make it Lambda based old platform.

 

[Mtrabeaux]

2017 Acadia Denali 3.6, Just had same issue, coolant temp reading 0, fan running full speed, steering assist reduced warning. I first replaced thermostat, which is doable, but not an easy task. Located on top of motor passenger side. Have to pull air Intake to get to it. Able to separate radiator intake pipe at the thermostat housing elbow and did not have to pull the fuel rails.

This did not resolve the issue. I then had to tear it all back apart to change the engine coolant temperature sensor which is located right next to thermostat housing. I suggest if you change thermostat just go ahead and replace this, as it is $15 and not much work while you have it torn apart. Dealer wanted $900 to replace thermostat. Took me 3-4 hours and cost $175 for both thermostat and sensor. Took 2 hours the second time I tore it apart for the sensor. After all that it did not resolve issue.

I then saw where one guy had battery cable replaced and I really just thought it may be a ECM issue at that point. So I went out and unplugged negative battery cable for about 10 minutes to reset ECM. And that worked, for now anyhow.

I’ve had several other electrical glitches with this car, like door locks not working right, brake lights staying on, etc. So I’d say if you are experiencing any issue with the 3.6 engine Acadia, unhook negative battery cable for 10 minutes which reboots ECM. Now here’s hoping that my issue does not come back and that this solution helps someone else.

The Engine coolant sensor is right next to the thermostat housing. It is on passenger side, on top center of engine. If you stand on the passenger side fender well, you can see both the thermostat housing elbow and the sensor. If you are having these same issues, you should try disconnecting the negative battery terminal for 5 minutes or so and see if this fixes your issue.

I have a 2017 SLT that was having the same issues. So before diving into the whole ECT sensor/Thermostat pool I decided to look at the battery terminal issue. I found a bit of corrosion around the negative terminal, I removed the terminal and cleaned it really well and replaced it. Its been about a week and that seemed to solve the issue, so anyone having this problem I would try this first. It may not be the same for everyone but it seems to be working for me. Also I found a GM service bulletin on this issue, it says it may be the sensor but may also need an ECM software update. The electrical issue may be the cause of a lot of the headaches people seem to be having with what seems to be a common problem. Here's the service bulletin # if anyone is interested 17-NA-390.

(mod edit: added link to cited bulletin)

 

[Stonerracing]

Ok. My 2017 acadia has been doing this intermittently off and on for a year. Lasts about a week. It just started doing it again today. So after reading this forum I tightened the negative and positive battery terminals without removing them and it didn't help. I tried staring it a couple more times and it still gave the power steering assist message and no a/c. So then i took off the negative terminal and cleaned it. Than i took off the positive terminal and cleaned it. Tightened the fuses next to it also. Put positive back on and tightened. Than negative back on then tightened. Sprayed battery protection on them. Started it back up and everything works again. I tried starting it 3 more times and it works great. I think the terminals are the ticket. Just wanted to share my experience