2009 Allure/Lacrosse

My temperature gauge of the engine is showing that it is cold even when I have driven for awhile.

I checked my codes and I pulled P0116.

I checked the fluid in the radiator and I saw fluid to the top with a cold engine. The heater blows nice and warm. My thinking is that I don't have a leak.

So from my understanding it could be two other things 1. The thermostat and/or 2 the temperature sensor.

What do you all think?

also - where is the temperature sensor located? A picture would be great but any type of description would help.


thank you in advance.

You should use a scanner to monitor Engine Coolant Temp (ECT) after the engine has warmed up. This will tell you if it is a sensor, or thermostat problem.

I was thinking of just replacing the sensor first. Wouldn't the temperature gauge on the dashboard work if the sensor was working? Since it is dead to the left (cold position) and doesn't move from that position, I'm leaning toward sensor.

My problem is that I don't know the location of the sensor. It is also freezing cold where I live and I don't want to be crawling in and out and up and down an engine for more than a few minutes.

My other reason for just changing the sensor is that it is relatively cheap and I don't have a scanner that can do real time measurements of temperature changes.

Which engine do you have, 3.6L 3.8L, or 5.3L?

I see you live in the Great White North. Are you dealing with temps below zero F? Like -10 or more? Do you have a block/coolant heater that you are using? If so, there is a Technical bulliten relating to the P0116.

I'm guessing you are out of warranty?

I'm just out of warranty by about 1000 km (approx 5-600 miles ). My engine is a 3800 and yes I do have a block heater.

How do I find this technical bulletin and what is it about exactly.

Just a little update. My wife was driving the car today and the temperature gauge in the car started to work today.

So maybe we are just looking at the electrical connector to the temperature sensor??? Still not sure where that sensor is on my 3800 engine though.

BTW - Temperature here yesterday was something like -14.5 F which isn't actually all that bad. It can get a hell of alot colder than that, but that still isn't fun when screwing around with a car.

BTW - Temperature here yesterday was something like -14.5 F which isn't actually all that bad. It can get a hell of alot colder than that, but that still isn't fun when screwing around with a car.
I can fell your pain! I was in Winnipeg during the 80's when it was -25 F with wind gust between 30-40-mph. The ECT sensor on a 3.8L should be located in the LIM under the throttle-body, drivers side. It is hard to see in that location.

Sorry, never mind. The bulliten only applies to the 8cyl model. Sounds like you have something going on with the sensor or a connection issue and you suggested. FYI though it involved moving the sensor from the front of the left side head to the back of the right side head.

Thanks for the assist guys. Of course the location of the sensor would need to be hiding under everything. Never on top and in the front.



thanks again