My cars check engine light came on yesterday while driving, so I checked the code and it was P128 (Coolant temp below regulating temp). There was also another one but it didnt give me a code just said pending, Im hoping this was because of whatever caused the first code and will go away. Is there anything I can do to fix this, will a battery disconnect do the trick or does a stealership get my money?

 

this code means engine not coming up to operating temp in correct time. did the CEL go off or is it still on? have you recently added any coolant? did you have the heater on high the whole time? is the title clean? ever had the radiator or water pump changed? check to see if the radiator fan is stuck on. or it could be that your thermostat is stuck open. with the crazy cold weather we have been having if it is off now i wouldn't worry about it

 

I have not added coolant recently, the light has stayed on since it has come on yesterday. I did not have the heater on immediately when I got on, I usually let the car warm up first then put it on. But after that I did have the heat on. Dont believe the radiator or water pump changed.

 

park the car and see if the fans kick on and off while it is at normal operating temp or if they just stay on. here is a link to the thermostat from auto zone. take it to them and see if the "pending" code comes up. they can check you codes for free. they can also erase the code and just see if it comes back. also know that if the problem really is just that the temp and not some other problem, it should not affect performance or MPGs at all.