What can a flashing blue light (without siren) mean?

In German traffic rules, a flashing blue light on a vehicle indicates it is an emergency or official vehicle on duty. When the blue light is flashing, even without a siren, you must give way because the vehicle might need to proceed quickly. Additionally, a flashing blue light can serve as an advance warning of a closed convoy, meaning a group of vehicles moving together under official or special conditions. Therefore, both these situations require you to be attentive and yield as necessary. The misconception is that blue flashing lights without a siren are meaningless, but that is not true—they always indicate special priority or warnings in German traffic law.