The 04 error code occurs along with the dishwasher’s sudden inability to dry dishes, and, in most cases, it caused by the failure of the relay, which is attached to the control board. Commonly, the control board is located inside the door. It can be accessed quickly, as the door is very easy to disassemble. This work requires a bit of knowledge, skills and experience, although the replacement of the relay is not a very expensive procedure. Please, use professional help.