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2008 Impala Thermostat sensor

2008 Impala 3.5L. Dash said “Engine hot, turn off A/C.” Temperature gauge read 0 on cold engine start. Took it to the shop and after diagnostic they called and said the thermostat sensor and the thermostat itself was shot. I had them replace the sensor alone. Drove the car for a week and everything was normal. Today I got the same “Engine hot turn off A/C” notice from cold engine start. What is going on?

So you didn’t replace it and now the engine is trying to overheat? Go figure!

Take it back and have the thermostat changed, it likely is failing and blocking your coolant flow.

Engine never overheated in the week I was driving. It gave the warning from a cold start.

I wonder if the mechanic cleaned the contacts on the connector before plugging it back in. It could be dirty contacts.

Yeah, sounds like the thermostat is getting stuck open or closed which makes the system think your having cooling issues. Replace the thermostat. And check the state of your coolant. Thermostat for your car should be pretty cheap at autozone. And since it’s being changed, make sure they use the dexcool branded coolant to refill what’s lost after the swap.

This does not make the thermostat suspect.

The problem is more likely the new sensor (least likely), its connections, or something else downstream electrically, up to and including the instrument panel.

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Do NOT get these parts at autozone

Of all the auto parts stores out there, it seems the autozone parts are the likeliest to NOT work properly, sometimes they don’t even FIT properly

That is what I was thinking.

I’d change an 11 y.o. thermostat anyway.
I do it at 10 y.o. as PM.
Did the mechanic use some troubleshooting skills before just changing the sensor?