What engine do you have? The temp gauge sensor is on top of the rear block, right behind the rear end of the valve cover, drivers side. That's the sending unit sensor for the gauge, the one inline of the water pump is the input for the computer. This is for the 2.5L though, not sure about the 6-cylinders.
You can take the sensor off, (recommend look at a new one at the auto-store), and then you'll confirm the thread size, they could vary per engine/year.