[TNGURL1218]

I have a 2019 GMC Terrain SLT 2.0L. My temp gauge went all the way to the left and was not reading temp and the fan continued to run after the engine was shut off. The research I saw showed a bad ECT (Engine Coolant Temperature Sensor) I took it to Auto Zone and that is what the machine said was wrong. I replaced the sensor and it worked for a DAY!!. When I disconnect the ground to shut the fan off it will work again for a short time. PLEASE help!! What else could it be?

 

[repairman54]

Aftermarket sensors are not reliable. Installing a genuine GM sensor is step one. If still having issues, then connectors and wiring needs to be inspected. Critter damage to wiring does happen more often than you would think.
Sensor failure is the most common issue.

 

[RIT333]

Did AutoZone read a code ? What was the code ?

 

[TNGURL1218]

Did AutoZone read a code ? What was the code ?

Yes. I don't remember the number or official Code but it was the Engine Coolant Temperature Sensor. I replaced with an GM sensor. I just don't know where to go from here. I would think if it was the Thermostat then I would still have the Check Engine light on and that would come up when tested

 

[TNGURL1218]

Aftermarket sensors are not reliable. Installing a genuine GM sensor is step one. If still having issues, then connectors and wiring needs to be inspected. Critter damage to wiring does happen more often than you would think.
Sensor failure is the most common issue.

It was a genuine GM sensor. I'm not sure what I am looking for on the wiring but I will start there!!

 

[repairman54]

This is where having a scan tool is important so one can see exactly what the computer is seeing.
No modern late model vehicle can be properly diagnosed without a scan tool when electrical problems arise.
It's the first step any shop does.
There can be multiple codes for any sensor. Parts store just give you a generic result and they are not trained technicians, far from it.
Other than sensor replacement and harness / connector inspection that's all you can really do without a decent scan tool and a shop manual with wiring diagrams along with some technical skills.