The oxygen sensor is very insensitive with respect to the direction of flow of the gas to be analysed. The electrodes of the sensor are essentially distributed at equal interspacing around the circumference of a cylindrical solid electrolyte layer and, specifically, respectively in alignment with openings which are formed in a hollow, tubular element surrounded by the electrolyte layer. A heating unit can be formed either on the inner surface or on the outer surface of the solid electrolyte layer.
