Abstract: A method providing diagnostics of operation of an internal combustion engine ignition coil further including at least one electric cable connecting the ignition coil to at least one spark plug installed in a cylinder head of the engine. The method temporarily introduces a voltage-controlled switch into the ignition circuit, causing the coil to supply a diagnostics voltage higher than a threshold value needed for the spark plug to form a spark, so as to cause a spark to form between the central electrode of the spark plug and a conducting element of the switch, and checks that a spark actually is formed in response to the supply.