BoilerFaultCodesThe 6 most common faults
Your boiler has detected that the water pressure is too low for it to operate safely and needs to be refilled.
Locate the external filling loop, which is usually a braided silver hose with two small valves.Slowly open both valves to allow water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close both valves tightly and the boiler should automatically reset and resume operation.
Your boiler’s water pressure has dropped too low for it to operate safely, causing the system to shut down.
Locate the filling loop (usually a silver braided hose with two small valves) underneath the boiler.Open both valves slowly until you hear water entering the system.Watch the pressure gauge on the boiler screen and close both valves firmly when it reaches 1.5 bar.
Your boiler has detected an electrical power issue or a drop in voltage, causing it to shut down for safety.
Check if there are any signs of a power cut or if other appliances in the home are struggling.Locate your boiler's power switch or fuse spur and turn it off for 30 seconds, then turn it back on.Press the 'Reset' button on the boiler control panel once power is stable.
Your boiler's internal computer parts are struggling to talk to each other, which means the system has shut down as a safety precaution.
Locate the power switch for the boiler and turn it off for 30 secondsTurn the power back on and wait for the system to rebootIf the code persists, press the Reset button on the control panel once
Your boiler has detected that the water pressure is too low to operate safely, so it has shut itself down to prevent damage.
Locate the internal or external filling loop (usually two braided hoses or blue levers under the boiler).Slowly open the valves to let water into the system while watching the pressure gauge.Close the valves firmly once the pressure reaches between 1.0 and 1.5 bar.Press the 'Reset' button on the boiler control panel to clear the fault.
Your boiler has received an 'alert' signal from an external part of your heating system, such as a smart thermostat or a safety accessory, which has told the boiler to stop running.
Check your thermostat or smart home app for any error messages or low battery warnings.Ensure any external pumps or safety switches attached to the system are powered on.Restart the boiler by pressing the reset button to see if the external signal clears.
on the Viessmann Vitodens 222-F B2TF
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
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
Affiliate links. We may earn a commission at no extra cost to you.