Abstract: A sensor element is proposed for an oxygen limiting current probe for the determination of the .lambda. value of gas mixtures, particularly the exhaust gases of internal-combustion engines, whose oxygen supply is provided by a short-circuit cell disposed upstream of the pumping cell of the sensor element. In this way the CO.sub.2 and H.sub.2 O transverse sensitivity of the sensor element is made ineffective. In order to obtain at the pumping cell a limiting current that is a linear function of the O.sub.2 partial pressure, a diffusion barrier must additionally be disposed between the short-circuit cell and the pumping cell.

Abstract: To facilitate manufacture of a sensor, particularly a polarographic sensor which has no sealing or heat expansion difficulties and only low heat capacity in the measuring range and electrical connections, a solid electrolyte (17) is formed as a plate extending transversely across a bottom opening (13) of a preferably ceramic tube (11), the plate having two electrodes (16,21) applied to its major sides. The side facing the opening (13) is covered with a ceramic layer (20) having a predetermined diffusion or migration resistance to oxygen molecules. The electrical connections are formed by a conductive track (15) extending on the inside of the ceramic tube, in contact with the sensing electrode on one side of the plate; and a counter head (23) connected to a conductive bolt or pin (24) and resiliently spring pressed against the electrode, and holding the plate (17) and the diffusion barrier (20) thereon in position in the sensor.