Navigator 2000 got Service Engine Soon with code P0125. That means Engine coolant Temperature always low. The navigator dashboard shows temperature on dashbord around 25% above cold when driving for about 10 minutes. The temperature rises from C towards H but stays around 20% to 25% but never goes up. Navigator runs fine. It could be thermostat bad or Engine Coolant Temperature Sensor.

Do you know where is temperature sensor located? How to test it? Any experience with this code?

Thanks
John