The invention relates to polarographic sensors to determine the concentration of certain components in the exhaust gas from internal combustion engines, having a pump cell, the cathode (12) of which has a diffusion barrier (13) and the anode (14) a diffusion barrier (15). The sensors are suitable as wide-band sensors to determine the concentration of certain components in lean or rich exhaust gases if they are also fitted with a non-loaded reference electrode for measuring the polarisation of at least one of the electrodes with respect to this reference electrode. The invention finally relates to the use of the polarographic sensors to control the ratio of the components of the fuel/air mixture fed to an internal combustion engine.
