Viessmann · Vitodens 100-W Boiler
The burner is in a fault state due to a synchronization error in its operational sequence. This indicates a timing or coordination problem within the boiler's control system.
Click steps to track your progress.
Reset the boiler by briefly turning off and on its power supply.
If the fault recurs, contact a qualified heating engineer for further diagnosis.
An engineer may need to replace the BCU burner control unit if the issue persists.