A method is provided for monitoring at least one yarn quality parameter and/or a parameter of a sensor by an electronic cleaner of yarn by means of an optical detector comprising a sensor with one or two rows of individual optical elements. The individual optical elements provide at their outputs an analog signal proportional to the intensity of its irradiation, the value of which is monitored during each measurement cycle. In the first and/or the second row of optical elements of the sensor, for each monitored parameter, individual optical elements of the sensor, are selected constituting an active zone for monitoring a particular parameter. The number of the optical elements in one active zone in one row is lower than the overall number of the optical elements in the corresponding row, and the output analog signal of the individual optical elements of the corresponding active zone is included in the evaluation of the particular parameter.