Lacrosse cxl won't reach operating temp!

[TheOmen86]

So I have a 2006 lacrosse cxl that has never gotten up to operating temperature the couple years I've owned it. I replaced the thermostat 3 or 4 times and the coolant temp sensor 3 times. The heat works but it's not "hot hot" has to be set at 90 to really even feel like heat. I changed the coolant and crudely checked the gauge accuracy by checking live data and using a laser thermometer thing pointed at the engine. It doesn't get hotter than 171°F in the Pennsylvania winters the p0128 code stays on for coolant temp heating up too slow. The fuel economy is also not very good either. Around 16mpg highway on average. Maybe that's just how crappy it is tho 😂 I'm now in up state new York and it's been a sweltering couple weeks with temps in the single digits and below zero. It is now staying at the 25% mark and doesn't go any higher. Usually in normal pa summer temps it gets up to 3/8 at the most. Idk what else to check. Engine runs super smooth and quiet. 99k miles. Also the previous owner rear-ended a SUV causing minor plastic damage and crushing the hood latch. Nothing hit the radiator from what I can tell. when I wrote this and took the picture It's been idling for 40 minutes. And the outside temp is correct at 21°. Thank in advance for any advice.

 

[MelsRegal]

What temperature thermostat did you install?
With AC off and a cold start, is the engine fan running?

 

[TheOmen86]

What temperature thermostat did you install?
With AC off and a cold start, is the engine fan running?

The last time I got one the guy at AutoZone said they had two options and suggested I try the higher temp so I did. Sorry I don't recall the exact temp tho. I'm sure it was higher than the 170 it's currently topping out at. My limited Research says the optimal temp is between 195 and 230. A retired Buick mechanic says they run on the hotter side to conserve fuel. fans aren't stuck on. They kick in after a few minutes but I'm assuming it's kicking on prematurely. (They also cut off and keep the temp steady at 25% when I'm moving or 3/8s or so idling like the picture.

 

[MelsRegal]

The last time I got one the guy at AutoZone said they had two options and suggested I try the higher temp so I did. Sorry I don't recall the exact temp tho. I'm sure it was higher than the 170 it's currently topping out at. My limited Research says the optimal temp is between 195 and 230. A retired Buick mechanic says they run on the hotter side to conserve fuel. fans aren't stuck on. They kick in after a few minutes but I'm assuming it's kicking on prematurely. (They also cut off and keep the temp steady at 25% when I'm moving or 3/8s or so idling like the picture.

I don't trust the thermostat you are using and it's unclear at what temperature your fans are turning on with AC off. The fans should come on no lower than about 215.

 

[TheOmen86]

I don't trust the thermostat you are using and it's unclear at what temperature your fans are turning on with AC off. The fans should come on no lower than about 215.

I'll see if I can get a temp when they come on