Evening all. I have an issue I was hoping you might be able to help me with.

I have a 2001 Monte Carlo SS with a rather peculiar temperature gauge issue.

When it's OVER 70 degrees outside, the temperature gauge works fine. But when it gets colder outside, the gauge goes down to zero and stays there. After a few hours of driving the "check engine" light comes on due to the fact that my Temperature gauge still isn't working. When it warms up over 70 degrees outside again...the gauge will start to work again...only after driving it for a little while.

I personally am guessing that it might be the temperature sensor. But I have no idea where to find it to change it. Do you think it's the Temperature Sensor? Or something else.

If it is the Temperature sensor...where exactly is it?

Thanks in advance!

 

I had a problem close to your what mine ended up being is that my thermostat was busted and stayed open all the time that might be the problem but maybe not because u said the temp does not move and with it being some what warm out i think that would cause your car to over heat.

 

Nope. Not overheating at all.

The temperature gauge was fine all summer...but now that the temperatures are getting cooler here in Jersey (below 70 degrees outside now)...now it's only working when it gets over 70.

Kinda weird, eh?

 

Hey guys. I have a 2001 and it does the same thing. I noticed it last fall. When spring broke around here the temp gauge started working again. Now that fall has started, the problem has returned. But I want you to try something. When you notice the gauge not working, try to run the air conditioner. The yellow indicater light will come on at the button but you will not get any cold air. The thing that I can not figure out is that when the motor warms up it still may not work for a good while. The temp sensor is mounted to the water jacket in your motor and I know the motor temperature gets to at least 170 degrees which is warmer than 70. If you guys figure out anything please post it. Thanks.[sm=signs003.gif]

 

Any new findings? My car is doing the same thing. When it is warmer outside, the temp gauge works. Now that it is cooler, doesn't move. Last week or two it was warm one day, once again, worked fine. Weird. Something else that is happening with mine is sometimes the elec fans will come on when the car isn't hot, sometimes as soon as I start it the first time in the mornings. I just changed the coolant temp sensor that is located beneath the therm housing, no change.

 

after doing a little more reading, it sounds like I need to get the code cleared our of the cars computer to make it recognize the new sensor. Anyone know if simply unhooking the battery for a period of time will do this or does it require hooking it up to a scan tool?

 

Unplugging the battery, to the best of my knowledge, will not clear the codes. You'll have to hook it up to a scan tool to clear it out. Otherwise, I've been told that after 40 cycles of turning the engine on and off, the code should clear (if there are not further problems).

 

It is my understanding that when a thermostat goes "bad" or is "busted", it's wide open at all times thereby allowing for maximum flowrate through the radiator, and subsequently maximum heat transfer from the coolant to the atmosphere. This would account for the "milder" temperature readings on the temp guage during the summer when the warmer air results in reduced heat transfer rates, and the "dead" temp readings during the colder fall and winter months. Try replacing the thermostat; doesn't take more than an hour if you do it yourself and shouldn't cost more than $30.

 

I did 2 things to resolve the issue. First I replaced the Coolant Temperature Sensor...but that didn't work. Then I had Autozone clear the code and everything went back to normal. But I wasn't satisfied enough.

So I bought a new thermostat just in case and installed it. I checked my old thermostat and it looked fine. It wasn't stuck open at all. But I still replaced it. I also flushed my coolant and replaced it with fresh Dex-cool.

No problems since.

If you replace your Coolant Temperature sensor...change the Thermostat at the same time. It'll give you more room to work with to get the Sensor out and replace it.

 

Yeah, I'm guessing all these problems are probably the coolant sensor. Mine wasn't stuck open either, but I figured for 5 bucks you might as well replace the thermostat too.