BoilerFaultCodesThe 6 most common faults
01
F78 High Engineer
Your boiler has lost communication with its external controls or internal wiring kit, preventing it from heating your home.
Full guide for F7802
F3 High Engineer
Your boiler has detected that the internal component responsible for clearing exhaust gases is not operating correctly, so it has safely shut down to prevent any unsafe buildup.
Full guide for F303
F4 High Engineer
Your boiler is lighting up, but the flame is cutting out shortly after, meaning your heating and hot water will not stay on.
Full guide for F404
F5 High Engineer
Your boiler has detected that it is running too hot and has automatically switched itself off to prevent any damage.
Full guide for F505
F6 High Engineer
Your boiler is struggling to read the temperature of the water flowing to your radiators, so it has turned itself off to prevent overheating.
Full guide for F606
F10 High Engineer
Your boiler's internal sensor that monitors the water temperature returning from your radiators has lost its connection, causing the system to stop heating to prevent damage.
Full guide for F10on the British Gas 330+
Main PCBIntelligent Wiring KitWiring HarnessFan assemblyFan harnessPCB
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 British Gas 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