A sensor for determining a concentration of gas components in gas mixtures having a first measuring electrode (mixed potential electrode) which has little or no catalytic effect on the establishment of an equilibrium in the gas mixture and a second measuring electrode (equilibrium electrode) which catalyzes the establishment of an equilibrium in the gas mixture as well as a solid electrolyte that is conductive for oxygen ions arranged between the two measuring electrodes, with the two measuring electrodes being exposed to the gas mixture. At least the first measuring electrode (16) is a cermet electrode, where at least one metal oxide component of the cermet electrode is capable of reversible incorporation of oxygen.

A measuring arrangement for the analysis of gas components in gas mixtures, having at least one electrochemical solid electrolyte test cell with at least one cathode in a diffusion channel is exposed to a gas mixture. The use of several cathodes wired one behind the other makes possible selective analysis of individual gas components. At the first cathode, oxygen is selectively pumped off by the use of specifically oxygen-ion-conductive layers so that another component of the gas mixture can be analyzed by the following electrode.

A sensor, particularly for determining the oxygen content in exhaust gasses of internal combustion engines, includes sensor element which is fixed in a metallic housing and a sealing flange which is integrally formed on the housing and rests on a sealing seat which is formed on an exhaust system. The sealing flange has two ring elements which are integrally formed on the housing and each have an inclined sealing surface, a hollow space being formed between the two ring elements inside the housing.

The invention is directed to a method for detecting the oxygen content in a gas to be measured. At least one concentration cell operating in accordance with the Nernst principle is provided. The concentration cell includes a measuring electrode communicating with the gas and a solid electrolyte and a reference electrode connected to the measuring electrode through the solid electrolyte. A pump-current pulse is applied between the reference electrode and the measuring electrode and, directly after the end of each pump-current pulse, the current flow between the reference electrode and the measuring electrode is reversed in a pulse-like manner.

In order to provide a method and arrangement for analytical determination of the relative amounts of exhaust gas components, except for water, but including hydrogen in the rich range or oxygen in the lean range, and for determining a .lambda. value, in which the exhaust gas sample can be taken at any arbitrary location, an arrangement is provided in which at least one portion of the exhaust gas is passed through a catalytic reactor (2, 22), a condenser (3,23) connected to the catalytic reactor to receive the gas passed through it, and, after passing through the condenser, the gas passes through an IR spectrometer and by a .lambda.-sensor. The oxidizable and reducible components of the exhaust gas are reacted with each other in the catalytic reactor which is heated to temperatures greater than 450.degree. C. The relative amounts of CO.sub.2, hydrocarbons and, if present, CO are measured with the IR spectrometer and either the relative amount of hydrogen in the rich range or of O.sub.2 +1/2 NO in the lean range is determined with the help of the signal (I.sub.p) from the .lambda.-sensor. A .lambda. value is calculated from the measured exhaust gas component concentrations or relative amounts.