Method and Device for Checking the Hydraulic Leak-Tightness in an Exhaust Gas Aftertreatment System for a Motor Vehicle

A method for checking the leak-tightness of hydraulic components in an exhaust gas aftertreament unit of an internal combustion engine is disclosed. The exhaust gas aftertreament unit uses an electric motor to pump a liquid reductant from a reductant reservoir to a reductant injector that is kept closed. The reductant pump is switched on for a first predetermined period, and the electric current consumed by the electric motor is detected during this period. After a predetermined standstill time has passed, the reductant pump is switched on again for a second period identical to the first period, and the electric current consumed by the electric motor is again detected during this period. The electric currents detected during the two time periods are compared with each other, and the leak-tightness of the hydraulic components downstream of the reductant pump is evaluated based on the result of the comparison.