BoilerFaultCodesThe 6 most common faults
01
Lack of power supply High DIY-safe
Your boiler is not receiving any electrical power, which stops it from working entirely.
What to try first
Check that the fused spur switch supplying the boiler is turned on.Check your home's fuse box or consumer unit to see if a trip switch or fuse has blown.Try plugging a lamp into a nearby socket to verify the electrical supply is working.
02
Faulty primary circuit High Engineer
Your boiler has detected that water isn't flowing properly through its internal heating pipes, so it has safely shut down to prevent damage.
Full guide for Faulty primary circuit03
Faulty air pressure switch High Engineer
Your boiler has stopped working because it cannot safely confirm that exhaust gases are clearing properly.
Full guide for Faulty air pressure switch04
Lack of burner ignition High Engineer
Your boiler is failing to start up because it cannot get the flame to ignite.
Full guide for Lack of burner ignition05
Safety thermostat lockout High Engineer
Your boiler has shut itself down safely because it detected that internal temperatures became too high.
Full guide for Safety thermostat lockout06
Faulty Electronic control/ignition p.c.b. High Engineer
Your boiler's main electronic brain is failing to control the ignition and operation properly, which usually results in a complete shutdown to keep your home safe.
Full guide for Faulty Electronic control/ignition p.c.b.on the Biasi Parva 28S
FusePrinted Circuit Board (PCB)Circulating pumpAutomatic bypass valvePlate heat exchangerAir pressure switch
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