FIELD: technological processes.SUBSTANCE: invention relates to testing the coating thickness in a coated catalyst region in car exhaust gas cleaning catalysts. Method for determining the coating length in a coated carrier for the manufacture of automotive exhaust gas converters is carried out as follows. Carrier has a first and a second end, an outer surface, a main axis and axis length L, and channels defined by the walls of the channels extending from the first to the second end parallel to the main axis, the method comprising: a carrier for the manufacture of automotive exhaust gas converters having a first temperature; providing a coating liquid having a second temperature being different from the first temperature of the carrier; aligning the carrier on a suitable means for introducing the coating liquid into the channels of the carrier; introducing the coating liquid into the channels of the carrier in such a way that a coating is formed on or in the channel walls, wherein the channels are coated over a
