Abstract: The invention relates to a method for testing the impermeability of components (1) that contain cavities (7). On at least one side of the component (1) to be tested, at least the surface to be tested is completely wetted with a foam-producing testing liquid (11). The aim of the invention is to create a method that can be carried out as quickly and easily as possible, during which the component (1) to be tested is influenced as little as possible by the testing liquid (11). To this end, the component (1) is subjected to an increase in temperature, and the surface of the component (1) to be tested is subsequently examined with regard to the formation of bubbles (12) in the testing liquid (11). The testing liquid (11) preferably consists of 10 to 20% dissolved surfactants, 2 to 6% alcohol, and 75 to 78% water and a maximum of 5% auxiliary agents.