The DTC code P0125 OBD2 means that the ECM (Engine Control Module) has detected that the heat in the cooling system is not sufficient, so that the fuel management system can take control. The ECM (Engine Control module) has a default value, so that after the engine starts, there is a coolant temperature.
Basically this diagnostic code indicates that the ECT sensor (Coolant temperature sensor) has not reached the temperature level that is needed to enter the closed loop operation in a specific time lapse.