Where is the coolant temperture sensor located on my 2000 chevy lumina

On the block ( the bottom part of the motor ) below the intake manifold

Is the radiator full? make sure there are no air pockets in the engine block. Check the coolant level often.

"TPS" stands for Throttle Position Sensor. It is located in the same place that all TPS sensors are located - on the throttle body.

This year doen't use a separate sensor for the cooling fans, it uses the ECT (engine coolant temp sensor) sensor that monitors engine temperature for the fuel control system, the computer turns the fans (via a relay) on when the engine reaches about 225-230 Degrees F

Coolant level sensor failures are common. It is located in the radiator tank on the right (passeger) side of the radiator. it looks like the picture below. Also, there has been a lot of problems with the connector for these sensors. (see picture) AutoZone stocks BOTH of these parts. Inspect the connector for breakage, corrosion and insulation peeling off of the wires. If there are no problems found with the connector, then you can probably just replace the sensor.

Sure the engine coolant will be warmer than the outside temperture and if the car has been sitting a long time in cold weather and the outside temperture warms up it could be the other way around. The coolant temperture sensers aren't real accurate as they are a relaitive senser beween hot and cold and the numbers reported don't have to be real just the change from hot to cold and the reching of the coolant to the operating temperture. Noe it the senser doesn't read the opertating temperture coprrectly you'll have all kinds of problems. The therostaste will try to set the temperture of the water to it's set temperture and can open or close completly to get 195 degrees F. Many times if it's too cold then the stat is bad and needs to be replaced This shows up in alot of cars first thing after winter and the first onset of cold weather when the daily tempertures vary the most from day to night.

It might not be related to the temperature but it can be due to failure of the thermister ( the temperature sensor) that is causing this erratic action.
So locate the sensor which is normally mounted on the area of the water pump .
Also check if there is any decolouration of the coolant if so flush and refill.

this is a common problem with gm vehicles your low coolant sensor is bad, depending on which engine you have,it will be located in the coolant jug, or it will be a 2" square sensor near the top of the passenger side of the radiator end tank

sounds like the gauge and sensor r workin properly....but you do have to address that coolant leak...that causes your temp to fluctuate cuz you cooling capacity is being reduced

It's held down by one bolt right above the timing chain cover. It's next to the head that's facing toward the front of the car.