BoilerFaultCodesThe 3 most common faults
01
Lockout lamp (red) on High DIY-safe
Your boiler is trying to light but cannot successfully create or detect a flame, causing it to shut down for safety.
What to try first
Check that your gas supply is turned on at the meterCheck if other gas appliances (like a hob) are workingPress the reset button to attempt a restart
02
Boiler ON (green) light off High DIY-safe
Your boiler has lost power completely, meaning it will not turn on or provide any heating or hot water.
What to try first
Check if other appliances in your home have powerCheck your main property fuse box to see if a circuit has trippedEnsure the boiler's power switch on the wall (fused spur) is turned on
03
Lock lamp / lock state High DIY-safe
Your boiler has entered a safety lockout mode and stopped working because it failed to light or stay lit through several attempts.
What to try first
Check that your gas supply is active and other gas appliances are workingLocate the reset button or selector switch on the control panelTurn the selector to the 'R' (Reset) position for 2 seconds and then back to the on position
on the Biasi Gaia
Ignition electrodeFlame detection probeGas valvePCBInternal F1 or F2 glass fusesMain Control PCB
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