JEEP Commander 5.7L P0128 code is on from beginning of cold start or hot start

Question

2006 Jeep Commander 5.7L P0128 code is on from the beginning of cold start or hot start, with normal coolant level.

Answer 1

P0128 Coolant thermostat malfunction,coolant temperature below regulating temperature. When you see this code replace the thermostat,that is a good starting point,Other than that inspect the radiator cooling clutch fan for proper operation,when the engine is cool to touch this fan should easily spin ,when the engine is operating temperature the fan should not easily spin,Other than that you are dealing with a mechanical condition