Method to control the sealing of a blow-by gas breather circuit of an internal combustion engine, comprising a separator device to agglomerate the particles of finely atomised lubricating oil and to remove the solid particulate particles and having an outlet connected by a pipe to an intake pipe through which the gas purified from the lubricating oil and the particulate flows out and a pressure sensor; the method providing the following steps: acquiring the signal coming from said pressure sensor; filtering the signal coming from the pressure sensor; integrating over time the square of the filtrated signal coming from the pressure sensor; and determining the sealing of the pipe according to the integrated signal which is the combustion energy generated by the internal combustion engine.