Patent ID: 8250855

Claim:
A method of dosing a reducing agent to an exhaust gas of a combustion engine by control of a valve having a solenoid and a movable seal body for adjusting a flow cross-section of the valve, wherein the flow cross-section has a shape dependent on an electric current passing through the solenoid, the method comprising: actuating the valve by using a current profile having a plurality of over time consecutive portions; adjusting the electric current to a first current level during a first portion of the current profile; assessing the status of the valve during the first portion, wherein it is determined if the valve is frozen or in danger of freezing; adjusting the electric current applied to the solenoid to a second current level during a second portion, wherein the magnitude of the electric current applied to the solenoid during the second portion is dependent on the status of the valve determined during the first portion; and determining if a course of amperage exhibits at least a first gradient and a further gradient, in that the first gradient adjusts at a first flow cross-section and the further gradient adjusts at a second flow cross-section, wherein a fed-in electric current is set to a low value if the course exhibits the first gradient and a second gradient and the fed-in electric current is set to a higher value if the course only shows the first gradient.