Monitoring the Ventilation of a Crankcase of an Internal Combustion Engine

Various embodiments include a method for monitoring the ventilation of a crankcase of an internal combustion engine with combustion chambers and a nitrogen oxide sensor arranged in an exhaust system, the sensor configured to detect an amount of nitrogen oxide in exhaust gas of the internal combustion engine. An example method includes: determining a predefined operating mode of the internal combustion engine defined by substantially no combustion of an air/fuel mixture taking place inside the combustion chambers; determining an amount of nitrogen oxide in the exhaust gas during the predefined operating mode of the internal combustion engine using the exhaust gas sensor; and identifying functional ventilation of the crankcase if the detected nitrogen oxide level exceeds a predefined nitrogen oxide threshold or identifying a malfunction if the detected nitrogen oxide level is below the predefined nitrogen oxide threshold.