BoilerFaultCodesThe 6 most common faults
01
Boiler locked-out High DIY-safe
Your boiler has shut itself down as a safety precaution and needs a manual reset to try and start up again.
What to try first
Check that the gas supply valve near the boiler and your gas meter are both in the 'on' positionLocate the reset knob labeled 'A' on the boiler control panelTurn the knob to the 'Reset' position, hold briefly, then release it to allow the boiler to attempt ignition
02
5 (Flashing Light) High DIY-safe
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
What to try first
Locate the external filling loop, which is usually a flexible silver braided hose with one or two small valves underneath the boiler.Open the valves slowly to allow mains water into the system while watching the pressure gauge on the front panel.Close the valves tightly once the needle reaches the green zone, typically between 1.0 and 1.5 bar.
03
F1 High Engineer
Your boiler is unable to light its internal flame, which means you currently have no heating or hot water.
Full guide for F104
F2 High Engineer
Your boiler has successfully lit, but it is unable to detect that the flame is actually burning, so it is shutting down for safety reasons.
Full guide for F205
F3 High Engineer
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Full guide for F306
F4 High Engineer
Your boiler has detected an issue with its internal ventilation, meaning it cannot safely remove combustion gases, so it has shut down to prevent potential danger.
Full guide for F4on the Ferroli Tempra 12 18
Ignition electrodeFlame rectification probeGas valvePCBFilling loopPressure gauge
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