An analysis of the operation of an amperometric sensor with a diffusion channel at unsteady pressure of the analysed gas was carried out. Relations between sensor parameters, pressure jump and sensor current were established. It was shown that the main reason for the distortion of a sensor reading is a large convective gas flow into the sensor chamber through the channel due to a gas pressure jump. On the basis of the analysis, it is demonstrated how to change the sensor parameters to eliminate the error in the sensor reading. This may be achieved by decreasing the sensor chamber volume or changing the diffusion channel parameters. Two types of diffusion channels are considered : a channel filled by a porous medium and a narrow plate channel. The relations obtained provide the basis for choosing the corresponding sensor parameters in order to attain a given accuracy of the oxygen concentration measurement for maximum expected pressure changes.