A method and apparatus for fault detection of a coolant diverter valve. The coolant diverter valve is arranged in a coolant system to control flow of coolant from a coolant reservoir to a diesel exhaust fluid tank. At least a first sensor is provided for measuring the pressure and/or temperature of the coolant. During operation of the coolant diverter valve, as required from time to time, the coolant diverter valve is commanded to open by energising the coolant diverter valve and commanded to close by de-energising the coolant diverter valve. Based on readings from the first sensor a controller can determine if the coolant diverter valve has failed to close when the coolant diverter valve is de-energised.

To provide a reducer supply device that can be made compact and has excellent maintainability. The reducer supply device includes a nozzle unit that adjusts a flow rate of a reducer which is to be supplied to a NOx purification catalyst device; and a pump unit that supplies the reducer to the nozzle unit. The nozzle unit and the pump unit are arranged at positions offset from each other in top view.

An exhaust aftertreatment system comprises: a transfer pump for conveying the reactant, a supply line for supplying the reactant to the exhaust stream, wherein the supply line has a fluid connection to the transfer pump, a pressure regulator designed to adjust the flow rate of the transfer pump depending on the pressure of the reactant in the supply line by way of a controller having at least one integral component. A method for controlling pressure in a supply line for supplying reactant includes the steps of: sensing the pressure of the reactant in the supply line, detecting whether a pressure curve of the pressure of the reactant in the supply line characteristic for the occurrence of air bubbles in the reactant occurs, and performing a reset of the integral component as a function of the detection of a pressure curve characteristic for the occurrence of air bubbles.

An exhaust aftertreatment system comprises: a transfer pump for conveying the reactant, a supply line for supplying the reactant to the exhaust stream, wherein the supply line has a fluid connection to the transfer pump, a pressure regulator designed to adjust the flow rate of the transfer pump depending on the pressure of the reactant in the supply line by way of a controller having at least one integral component. A method for controlling pressure in a supply line for supplying reactant includes the steps of: sensing the pressure of the reactant in the supply line, detecting whether a pressure curve of the pressure of the reactant in the supply line characteristic for the occurrence of air bubbles in the reactant occurs, and performing a reset of the integral component as a function of the detection of a pressure curve characteristic for the occurrence of air bubbles.

A method and apparatus for fault detection of a coolant diverter valve. The coolant diverter valve is arranged in a coolant system to control flow of coolant from a coolant reservoir to a diesel exhaust fluid tank. At least a first sensor is provided for measuring the pressure and/or temperature of the coolant. During operation of the coolant diverter valve, as required from time to time, the coolant diverter valve is commanded to open by energising the coolant diverter valve and commanded to close by de-energising the coolant diverter valve. Based on readings from the first sensor a controller can determine if the coolant diverter valve has failed to close when the coolant diverter valve is de-energised.