[JPelectrical3825]

Thanks for the detail.
I see other GM cars and trucks have had the same issue.
In some cases, it was the T-stat.
In others apparently not.
I blame it on an over complicated mess what with all the modules "checking in" and having to chat over that internal vehicle network.
More and more it's sounding like some intermittent connection somewhere or. . . . just some coding error or timing error in the data. But why would the engine coolant temperature data have to be so glitchy then ?
Such a pricey and pain in the butt job to replace that T-stat and/or ECT sensor only to find out they are not the problem.

Kind of why I'm holding off on the swap. I do have all the parts. But I want to know if I can actually nail down the real issue. Cause obviously I'm reading temp on my scanner even when the vehicle isn't.

 

[HStevenLee]

I have a 2018, and I had the same problem a few months ago. The dealer replaced the thermostat and the sensor. The problem being is that the thermostat malfunctions and the engine wont heat up enough to satisfy the sensor. It throws a hidden code p1028?.

the repair out of pocket is about $1400. So be ready.

 

[JPelectrical3825]

I have a 2018, and I had the same problem a few months ago. The dealer replaced the thermostat and the sensor. The problem being is that the thermostat malfunctions and the engine wont heat up enough to satisfy the sensor. It throws a hidden code p1028?.

the repair out of pocket is about $1400. So be ready.

I don't pay people to work on my vehicles. So repair for me is going to be about $350.
But I proved the sensor still reads. Even though it's in the 166-172* range. That could be because the fan doesn't shut off and commanded at 80%. If it was a mechanical issue the problem wouldn't just go away simply by erasing a code.