Method and Device for Diagnosing a Crankcase Ventilation Line for an Internal Combustion Engine

Various embodiments include a method for diagnosing a crankcase ventilation line of a crankcase ventilation device for an internal combustion engine having a crankcase, an intake tract, and a compressor arranged in the intake tract for compressing the intake air comprising: diverting fresh air from the intake tract via a fresh air supply line; either enabling or inhibiting a flow of fresh air into a free volume of the crankcase depending on a switch position of a shut-off valve in the fresh air supply line; detecting a nitrogen oxide concentration in the crankcase during the process of crankcase ventilation, close to the point of introduction into the intake tract upstream of the compressor using a nitrogen oxide sensor; and evaluating the tightness of the crankcase ventilation line based at least in part on the detected nitrogen oxide concentration.