So I have been having this issue intermittently that has my radiator fan stay on as soon as the engine is started. When I turn on the A/C that would normally kick the fan on, the fan still stays on as it should. When I turn off the A/C, the fan stays on. It caused me to throw P0128-Powertrain. Coolant Thermostat. The fan has done this three times in the past week, but has not done it for two days now. Could it be the relay?

The coolant temperature sensor malfunctioning in a certain way will throw the fan on all the time. This sensor won't usually throw a code tho. The sensor is located in different spots depending on your motor. Also, does the temp gauge work?

Temp gauge works just fine. The code was for the thermostat not opening up while the engine was running because of how low the engine temp was staying at (130*-140*F) the whole time. It's a 2003 with 180,xxx miles.