Abstract: A method for processing the ion flow signals of internal combustion engines by offset correction, masking and multiplexing for engine control functions wherein, after the measurement of the ion flow signal in each cylinder for the purpose of offset correction in advance of each ignition operation, the level of the measurement signal of the cylinder is detected; during masking operation, the measurement signal is substituted in a second signal by the level value and is subtracted from the second signal until the next ignition operation and thereafter, the channels which are to be multiplexed, are combined to a third signal by the addition of the second signals of the particular cylinders, the second signal being derived from the measurement signal.