BoilerFaultCodesThe 5 most common faults
Your boiler's burner has shut itself down for safety because it failed to light or maintain a flame.
Check that you have fuel in your oil tankEnsure the oil supply valves are fully openPress the illuminated reset button on the burner control unit once
Your boiler has detected a problem with the burner and has shut itself down as a safety precaution, meaning you will not have any heating or hot water.
Check that you have not run out of heating oil in your storage tankEnsure the oil shut-off valve is fully openPress the reset button on the burner control unit once to see if the boiler restarts
Your boiler is failing to start up when it is supposed to be heating your home.
Check if your fuel tank has enough oilPress the reset button on the burner controller onceEnsure the external oil supply valve is fully open
Your boiler has stopped heating because it has detected a problem with the internal pump or water circulation.
Check that your home's radiator valves are fully openInspect the boiler pressure gauge and ensure it is between 1.0 and 1.5 barPress the reset button on the control panel once
Your boiler's internal computer is missing a specific identification card needed to recognize how your heating system is configured, causing it to stop working for safety reasons.
Full guide for b7on the Viessmann Vitorond 100
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Viessmann shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue