Despite his enormous physical enhancements, Brainiac had several weaknesses. Like the Pre-"Crisis" Brainiac, he is mentally connected to his ship in such a way that he can be disabled for a short period if separated without warning. Initially, he had the weakness of being disabled by his mysophobia and sensory overload when dumped into Earth's atmosphere, though he does not seem to have this defect in his later battles on Earth, such as when he defeated Superboy, suggesting that he had fixed it, or that he is only overloaded in particularly dirty environments. Finally, being separated from his ship for prolonged periods causes him to physically deteriorate and become far less powerful, as Lex Luthor observed while studying his unconscious body over the course of several days when it was in the custody of the U.S. government.