BoilerFaultCodesThe 4 most common faults
01
lock-out light High DIY-safe
Your boiler has shut down for safety because it either failed to light, sensed it was getting too hot, or detected an issue with how it clears waste gases.
What to try first
Check that your gas pre-payment meter (if applicable) has credit.Ensure any external gas isolation valves are fully open.Press and release the reset button on the front control panel to see if the boiler restarts.
02
All Lamps OFF High DIY-safe
Your boiler appears to have no electrical power at all, meaning the screen and lights are completely blank.
What to try first
Check if the boiler's power switch is turned onCheck your home's main fuse box (consumer unit) for a tripped circuit breakerCheck the fuse in the spurred power socket next to the boiler
03
Lock---out signal lamp red High Engineer
Your boiler is failing to recognise that the flame has lit, causing it to repeatedly try to spark before shutting down for safety.
Full guide for Lock---out signal lamp red04
All Lamps ON High Engineer
Your boiler's internal computer has suffered a critical failure and can no longer control the heating or hot water functions.
Full guide for All Lamps ONon the Biasi Garda M90f
Ignition ElectrodeSafety ThermostatAir Pressure SwitchGas ValveElectronic Control PCBInternal Fuse
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