BoilerFaultCodesThe 6 most common faults
01
F37 High DIY-safe
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
What to try first
Locate the external filling loop, usually found underneath the boiler.Open the filling valve slowly to let mains water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close the valve tightly once the correct pressure level is reached.
02
F43 High Engineer
Your boiler has detected that the main heat exchanger is getting too hot, so it has shut itself down to prevent any internal damage.
Full guide for F4303
Sc14 High Engineer
Your boiler has detected an internal issue with its combustion control system and has safely shut down to prevent incorrect operation.
Full guide for Sc1404
A01 High Engineer
Your boiler is failing to light the flame needed to heat your home's water and radiators.
Full guide for A0105
A05 High Engineer
Your boiler has detected an issue with the internal fan that pushes exhaust gases out of the flue, so it has safely shut down to prevent unsafe operation.
Full guide for A0506
A06 High Engineer
Your boiler is correctly attempting to start, but it is failing to light the internal gas flame required to produce heat or hot water.
Full guide for A06on the Ferroli Bluehelix Tech RRT 24C
Filling loopPressure relief valvePressure sensorTemperature sensorsPrimary heat exchangerPump
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 Ferroli 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
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