Abstract <p>The possibilities of carrying out the tolerance check of spark discharges parameters in semiconductor spark plugs of the capacitive ignition systems are analyzed based on measuring two diagnostic quantities using easily accessible methods: the voltage on the storage capacitor at the moment of transition of the discharge preparatory stage to the spark stage in the spark plug and the residual voltage on the capacitor at the moment of discharge extinction. Based on experimental studies of discharge processes in a capacitive ignition system, including the use of an original circuit for cutting off the discharge current in a spark plug at the end of the discharges preparatory stage, the distribution laws of diagnostic parameters were determined and confirmed for use in tolerance check of the capacitive ignition systems efficiency. </p>