19. Error message "Check external security" on the Labsys Evo.

A device safety device has tripped to prevent heating.
1. Flow of water that is too low. (prerequisite: 2 l / min 3 bar)
2. Error on the direction of water flow.
3.Electromagnetic water faulty.
4. The thermal switch on the furnace body has tripped because the water temperature is too hot.