BoilerFaultCodesThe 6 most common faults
Your boiler has overheated and shut itself down as a safety precaution to prevent damage.
Check that all radiator valves and boiler isolation valves are fully openPress the 'Reset' button or turn the control knob to the 'Reset' position for a few secondsEnsure the system pressure is between 1.0 and 1.5 bar on the pressure gauge
Your boiler has detected an internal error and has shut down its burner for safety, meaning you will not have any heating or hot water.
Locate the reset button or dial on the front control panelPress or turn to the 'Reset' position for 2 to 3 seconds, then releaseWait for the boiler to attempt to restart; if the code returns immediately, call a qualified engineer
Your boiler has detected a problem during the star-up sequence and has shut itself down for safety.
Press the 'Reset' button or turn the rotary selector to 'Reset' for two seconds.Ensure your gas supply is active (check other gas appliances like a hob).Check that your condense pipe has not frozen if it is currently cold weather.
Your boiler has failed to ignite or stay running, meaning you currently have no heating or hot water because the burner is not firing.
Check if your gas supply is active (test a gas hob or check your meter credit)Press the Reset button or turn the control knob to 'Reset' for 5 secondsEnsure the system pressure is between 1 and 1.5 bar
Your boiler has detected that the water pressure is too low for it to operate safely, causing it to stop providing heating and hot water.
Locate the filling loop (the silver flexible hose) underneath your boiler.Slowly open both taps/hand-wheels until you hear water flowing and the pressure gauge rises.Close both taps tightly once the needle reaches 1.5 bar, then reset the boiler.
Your boiler has stopped working to prevent damage because the burner is failing to ignite or detect a flame correctly.
Check if other gas appliances in your home are working to ensure your gas supply is activeEnsure your pre-paid gas meter has creditLocate the reset button (usually a dial or a specific button marked 'R' or 'Reset') and hold for 2 seconds
on the Viessmann Vitopend 111
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