BoilerFaultCodesThe 6 most common faults
01
F1 High DIY-safe
Your boiler has stopped working because the water pressure inside the system is too low to operate safely.
What to try first
Locate the filling loop (usually a silver braided hose with one or two valves underneath the boiler).Open the valve(s) slowly to allow mains water into the system while watching the pressure gauge on the front of the boiler.Close the valve(s) tightly once the needle reaches the green zone, typically between 1.0 and 1.5 bar.
02
L1 High Engineer
Your boiler has lost communication with its internal memory chip, meaning it cannot operate safely until the settings are restored or the component is replaced.
Full guide for L103
L2 High Engineer
Your boiler has detected that it is getting too hot or cannot move water through the system, so it has safely shut itself down to prevent damage.
Full guide for L204
F3 High Engineer
Your boiler has detected that the internal fan is not spinning correctly, which prevents it from safely venting gases, so it has shut down to protect your home.
Full guide for F305
F7 High Engineer
Your boiler is struggling to operate because the electricity supply from your home is too weak or unstable.
Full guide for F706
F2 High Engineer
Your boiler's internal computer is having trouble communicating with its configuration settings, meaning it cannot safely start up.
Full guide for F2on the Ideal Independent C24
Filling loopPressure relief valvePressure sensorBoiler Control Card (BCC)Wiring HarnessCentral heating pump
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 Ideal 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