The method involves allowing exhaust gas flow to act on a nitrogen dioxide sensor (7) in a measurement space (6) surrounding the sensor during measurement phases. The sensor is kept free from the exhaust gas flow between the measurement phases by exposing the measurement space to flushing gas i.e. air, immediately after each of the measurement phases such that exhaust gas present in the measurement space is displaced out of the measurement space into the exhaust gas flow. The sensor is exposed to calibration gas in calibration phases. Independent claims are also included for the following: (1) a device for an exhaust gas regulation system of an internal combustion engine (2) a vehicle.