I need to know where the coolant temperature sensor is?

The coolant temp sensor is on the driver side under the air intake duct on the rear cylinder head make sure you apply thread sealant to the threads of the new sensor upon installation to prevent leaks also use only dex-cool coolant if you add green or any universal coolant to the dex-cool it can cause engine damage also there is a small bleeder screw on the thermostat housing or on a bypass pipe on the passenger side of the engine remove one or both depending on which engine you have when you refill the coolant replace the screw(s) as soon as a steady flow of coolant comes out then finish topping off coolant as normal

Here is a guide to help walk you through the steps with the location of the coolant sensor in the diagrams below.

https://www.2carpros.com/articles/coolant-temperature-sensor-cts-replacement

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.