"Engine is cold too long"...what exactly does that mean?

 

Engine is too cold I'm guessing?

Either by unable to reach proper operating temps due to weather conditions or faulty thermostat.

 

it meant the engine coolant is not reaching the correct operating temperature, most likely caused by a thermostat stuck open, even in the coldest of temperatures the engine should eventually warm up since the stat stays closed until the water temperature reaches a certain point.