Temperature Gauge Doesn't go up, 01 Impala

danrose

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Hi, I have a 2001 Impala, and since its been very cold the last week (10 degrees), My temp. gauge hasn't moved from below 140 degrees even on long drives. My coolant level is ok, and I am still getting heat in the cabin. Do I have a bad gauge or sensor, or should I be looking at something else? Thanks!
 

Paul

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Is the original coolant still in the cooling system?You can verify the coolant temp at the thermostat housing,upper and lower radiator hoses using a non contact thermometer.Even on a cold day like you mentioned the coolant temp should be in the 190 to 200 deg range.I would suspect the thermostat is stuck open and needs replacing.If in fact the temp reading on the instrument panel gauge is correct,by running that cool the fuel mixture will be richer than its needs to be and dropping your mpg down a little.
 

kev2

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I am wondering is the SERVICE engine light on??
 

Gus

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I agree with Kev....if your temp actually is 140F, this should set a P0128.....the PCM monitors how long it takes for the engine to get to normal operating temp, from a cold start...if it takes too long, or doesn't reach normal operating temp, it should set this code....

If you are getting normal heat out of your vents(should be 145-160F, full hot), and no code is set, I would assume it may be a gage problem.....only way to know for sure is to look at actual ECT data on a scan tool and compare it to the gage....
 

big al

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Thanks guys! I did get a po128 code yesterday. I am going to change out the thermostat today.
 

buzzstpoint

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What cluster do you have?
Speedo, fuel and temp? Any others.

If you start your car, does the fuel and temp swing to full then back to normal?
I'd start with the thermostat. It's the cheapest. Then test the coolant temp sensor.
 

NickD

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Most OE thermostats will stay open when shot, where some aftermarkets will stay closed, much nicer to live with cooler temperatures than to have a head gasket blow or a plastic intake manifold melt. Be thankful your thermostat is staying open, though some aftermarket high priced thermostats do have a failsafe feature, and extra valve that pops open if the temperatures get too high. This is not a place to save a couple of bucks.

Like the guys said, check the thermostat housing temperature, if your hand has experience, good enough, big difference between 140 and 195. Not that I am paranoid, just experienced, like to put that new thermostat in a pot of boiling water with a cooking thermometer on the stove to know exactly at what temperature its cracking open at and indeed, it does open. Brand new out of the box always doesn't work and a lot of extra work to replace it if it doesn't. Ha, whatcha cooking dad? Thermostat soup.
 

Gus

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Nick, my Service Manager asked me what I was doing.....told him I was checking the opening temp of the thermostat by boiling it.....you don't want to know what he said! :)
 

NickD

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Gus, not sideways, I hope, LOL. The reason why they make guys service managers is because they don't know how to fix stuff. Thermostats do come from the factory closed, unless it's a very hot day, nice to see if they open before putting them in.
 

big al

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New thermostat solved the problem. Thanks to all who helped!!!!!!!!!!!
 
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