How many coolant temp sensors do we have? And what is the correct part #?

First question:

How many coolant temperature sensors do we have? I know there is one underneath the TB on my SC'd engine, which is the one I want to replace if this the one that affects emissions and mileage.

Second:

There are several different part numbers for the temp sensor. ACDelco even has 2 (213-928 and 213-4396) and they both look the same...one just has preapplied sealant, the other doesn't. Does anyone know which is correct for my application?

Thank you.

The sensor threaded into the lower intake under the throttle body area is the only coolant temp sensor for the engine and absolutely the one that the computer uses for affairs of emissions and such. The gauge also gets fed that temp signal via the pcm.
As for the part number I just looked up the numbers and listings show all sorts of different things. It wouldn't surprise me if either one worked fine - just get the one with the thread sealant on it and make sure it's a two pin if you have two wires for your harness. Some have 3 pins.

I ordered the 213-928 from Amazon for about $12 shipped. Will update on fitment once I install it.

213-928 installed, exact fit for threads and wiring harness plug. Will check any changes with emissions or MPG over the next few weeks. The one I took out was pretty nasty looking.

My car seems to be running smoother with the new CTS. Also, on cold mornings my car would be its own smoke show from all the smoke coming out the exhaust...the amount of smoke coming out has been reduced significantly since changing the sensor. Is there an explanation for this? Old sensor possibly reporting wrong temperature values and making the car run richer on startup, perhaps?

billfrank85 wrote:

My car seems to be running smoother with the new CTS. Also, on cold mornings my car would be its own smoke show from all the smoke coming out the exhaust...the amount of smoke coming out has been reduced significantly since changing the sensor. Is there an explanation for this? Old sensor possibly reporting wrong temperature values and making the car run richer on startup, perhaps?

It's definitely a contributing factor....