The DTC code P0481 has to do with the motor cooling fan circuit. When the vehicle is running, the necessary amount of air passing through the radiator effectively cools the engine but when the vehicle stops, there is no air passing through the radiator because the temperature starts to rise.
The Coolant Temperature Sensor(ECT) gives a signal to the Powertrain Control Module, which can detect the increase in the engine temperature. As soon as the temperature is in its maximum level, which varies by the vehicle manufacturer, the PCM commands a relay to start the fan.
If there is a problem within this circuit that stops the appropriate function of the fan, it causes the motor to overheat when driving at low speeds or when stopped, this fault code is set.