BoilerFaultCodesThe 6 most common faults
01
F1 High DIY-safe
Your boiler has stopped working because the amount of water circulating inside the system has dropped below the required level.
What to try first
Locate the filling loop, which is usually a flexible silver hose with one or two valves underneath the boiler.Gradually open the valve(s) to allow mains water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Close the valve(s) tightly and check that the fault code has cleared.
02
FU High DIY-safe
Your boiler has shut down because the water inside is heating up too quickly and cannot circulate through your radiators properly.
What to try first
Check all radiator valves in your home are turned to the open position.Ensure the large isolation valves located directly underneath the boiler are in the 'open' position (handle in line with the pipe).Switch the boiler off at the mains for 60 seconds and then turn it back on to reset the fault.
03
L1 High Engineer
Your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage or safety issues.
Full guide for L104
F2 High Engineer
Your boiler is trying to start but cannot detect a flame, so it has safely shut down to prevent gas from escaping.
Full guide for F205
L2 High Engineer
Your boiler has stopped working because it cannot light the flame or keep it burning safely.
Full guide for L206
LC High Engineer
Your boiler has attempted to restart itself too many times in a short period and has now locked itself for protection.
Full guide for LCon the Ideal GB24 / GB30
Filling loopPressure gaugePressure relief valveCentral Heating PumpPlate Heat ExchangerFlow Sensor
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