BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
Locate the external filling loop, which is a flexible braided hose connected to two valves beneath the boiler.Open both valves slowly to allow water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close both valves tightly and ensure the pressure gauge remains stable.
Your boiler has lost all electrical power, meaning it cannot operate your heating or hot water at this time.
Check your home's main fuse box or consumer unit to see if a trip switch has turned offEnsure the boiler's fused spur switch located near the unit is in the 'on' positionCheck if the fuse inside the fused spur has blown and replace it with a 3-amp fuse if necessary
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Locate the external filling loop, which is usually a flexible silver hose connecting two pipes underneath the boiler.Open the valves at both ends of the filling loop slowly to let water enter the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone, ideally around 1.5 bar.Close both valves tightly and remove the filling loop if required by your specific installation.
Your boiler is failing to light the burner because it cannot detect a flame, so it has safely shut itself down to prevent gas buildup.
Full guide for AnYour boiler has encountered a general safety error and has shut itself down to prevent damage, requiring you to attempt a reset before calling for professional help.
Full guide for ErYour boiler is failing to light the flame or keep it running, so it has safely shut itself down to prevent a gas build-up.
Full guide for Er 25on the Biasi Advance Plus 16S 25S 30S
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 Biasi 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