Why are you required to have a defective exhaust system repaired immediately?

You are correct that a defective exhaust system must be repaired immediately because of noise pollution and the risk that parts of the system could fall onto the roadway. In Germany, the exhaust system is essential for reducing harmful emissions and minimizing noise from the engine. If it's damaged, it can create excessive noise that disturbs others. Additionally, loose or broken parts may detach and create dangerous obstacles for other road users. The engine overheating is not a typical concern related to a defective exhaust system, so that option is not applicable here. Understanding these reasons helps ensure vehicle safety and environmental protection on German roads.