This past Thursday, my CEL came on and took it to Advance immediately for a code test. P0128 is what they gave me. I got this car with 266xxx miles on it in November 2015. I have put 15k (281,142) miles on it as of now. Ever since I have had it, it takes the car approximately five minutes to warm up. My car is not over heating at all but the temperature gauge needle usually takes 2 minutes to move. I know the P0128 code could be between the sensor, thermostat, or alerting coolant level. It is not extremely low but towards the minimum level. Is it best to go ahead and replace the thermostat? Much appreciated!