A method pertaining to an HC dosing system for cleaning exhaust gases from an engine (150). A dosing unit supplies fuel to an exhaust duct (240): Determining (s340) whether there is an undesired temperature level of the dosing unit. If that is found, removing (s360) warmed fuel from the dosing unit (250) by supplying it to the vehicle's exhaust duct (240), entailing calculating (s350) and removing an amount of fuel based on a prevailing temperature of the dosing unit (250), or removing (s360) a predetermined amount in the form of substantially all of the warmed fuel of the dosing unit and transmitting it to the exhaust duct. Also computer programme product containing programme code (P) for a computer (200; 210) for implementing the method. Also to a device and a motor vehicle (100) which is equipped with the device are disclosed.