Circuit/System Description

As reductant will freeze at temperatures below -11°C (12°F), there are 2 reductant heaters located in the reductant tank. One heats the reductant in the tank and one heats the reductant supplied to the reductant injector supply pipe. The ECM monitors the reductant temperature in the tank in order to determine if reductant temperature is below it's freeze point. If the ECM determines that the reductant may be frozen, it activates a "defrost strategy" energizing the reductant heater. This energizing action terminates when the temperature sensor measures a threshold value over which the heater must be deactivated.