I pulled a 125 code today on a very long drive,it's was 26 degrees outside and going 70 the temp barely went past the C running very cold ,any suggestions, thanks

 

P0125 = Insufficient Coolant Temperature for Closed Loop Fuel Control
Engine coolant is not warming up enough

With engine cold start it up and pop the hood
Feel upper radiator hose, it will be cold.

Let engine idle for 3 minutes, feel upper hose again, if it is warming up with the engine then thermostat is stuck open, needs to be replaced.

No engine coolant should be flowing in the upper hose until coolant in the engine gets to 190degF, thermostat is 192degF, needle on dash board temp gauge would be between 1/3 and 1/2 at that time.
temp gauge should run just below 1/2 when engine is fully warmed up.

The dash board gauge uses a SENDER on the thermostat housing.
The Code P0125 comes from ECT SENSOR right next to this SENDER, only computer uses this sensor.
The two are not connected in any way

So for both the needle to be low AND getting code P0125 I would have to believe thermostat was stuck open all the way

 

Thanks ron as soon as the weather gets into the 30 s it does this it's fine in warmer weather, what's the spec Stat rated 192 correct

 

192degF or 195degF can be used, not 160 or 180degF

Also make sure it has a Jiggle Valve.............yes that is actually what it is called, it is a small hole in the thermostat plate that has a metal pin in it, it lets air out when refilling the system or if you get a leak in the system, it prevents air from being trapped behind thermostat plate.
The Pin "jiggles" to keep hole from getting plugged up over time, "valve" part is a little overstated IMO, lol