Method for determining low filling level of e.g. liquid urea-water solution in flat tank for selective catalytic reduction of nitrogen oxide compound in exhaust gas in motor car, involves changing monitoring step if level plane is exceeded

摘要

The method involves monitoring whether a reserve filling level plane (9) is lowered, and computing filling level reduction if the reserve filling level plane is lowered. Computed filling level information is provided if the reserve filling level plane is lowered. Another monitoring is implemented whether the reserve filling level plane is exceeded if the reserve filling level plane is lowered. The former monitoring step is changed if the filling level plane is again exceeded, where a cross sectional area (24) corresponds to five times the square of height (23) of a tank (1). An independent claim is also included for a motor car that comprises a dosing unit.