Abstract: A method for evaluating a service interval for replacing a filter of a system for extracting an aqueous liquid from a motor vehicle tank in response to the risk of progressive clogging of said filter from use. A compound clogging risk decision value (K) is generated (320) on the basis of the sum of a plurality of elementary values (k1, k2, k3, k4) of the clogging risk, each related to a risk criterion depending on the operation of the extraction system since commissioning of the filter. The compound clogging risk decision value is compared (340) to a threshold value, and an alert to replace the filtration device is generated (351, 352) if the compound clogging risk value exceeds the threshold value.

Abstract: An axial extension part is proposed which makes it possible to use a filter cartridge (25) of larger axial dimensions than a standard filter cartridge for which the axial depth of a hollow housing (11) of a casing (10) of a selective catalytic reduction (SCR) device has been provided. This makes it possible to have different filtration characteristics without having to modify the casing. The larger filter cartridge (25) can be inserted into the extension part when this part is mounted in the housing (11) of the casing (10). The cartridge is sealed therein when the sealing cap (21) is put in place to close the opening at the rear end of the part.

Abstract: A method for controlling a return valve of an exhaust system and to an exhaust system with a control unit which is configured to carry out the method. The method is based on the object of avoiding an overpressure in the line system for urea solution as a result of a reduction in the injection rate. The method includes the steps of determining whether one or more of the following states are present during the operation of the exhaust system: a) an injection rate per unit of time of urea solution of the dosing valve is less than or equal to a predefined injection limit, b) a pressure measured by the pressure sensor in the line system overshoots a predefined first upper pressure limit (P2). The return valve is opened for a first predefined opening duration (?t1) if states a) and b) are present and at least one of the states has already been present for at least a predefined period of time (?ta). The return valve is closed after the first predefined opening duration (?t1) has elapsed.

Abstract: A method for controlling a return valve of an exhaust system and to an exhaust system with a control unit which is configured to carry out the method. The method is based on the object of avoiding an overpressure in the line system for urea solution as a result of a reduction in the injection rate. The method includes the steps of determining whether one or more of the following states are present during the operation of the exhaust system: a) an injection rate per unit of time of urea solution of the dosing valve is less than or equal to a predefined injection limit, b) a pressure measured by the pressure sensor in the line system overshoots a predefined first upper pressure limit (P2). The return valve is opened for a first predefined opening duration (?t1) if states a) and b) are present and at least one of the states has already been present for at least a predefined period of time (?ta). The return valve is closed after the first predefined opening duration (?t1) has elapsed.