BoilerFaultCodesThe 6 most common faults
Your boiler has stopped running for safety reasons and needs to be manually restarted to try and get your heating and hot water back on.
Why it happens: This fault occurs when the boiler attempts to light the burner but fails to detect a stable flame. The most common reasons include a lack of gas reaching the unit, worn-out spark components that cannot ignite the fuel, or a sensor that is too dirty to recognize that a flame is actually present.
Locate the reset button on the front control panel.Press and hold the reset button for at least one second.Wait for the boiler to restart; if the light stops flashing, the boiler should resume normal operation.
Your boiler has detected a general internal fault and has locked itself out to prevent damage.
Why it happens: This fault occurs when the boiler's internal computer identifies a communication failure between vital components, most often involving the fan or the air pressure switch. It acts as a safety shutdown because the system cannot confirm that harmful exhaust gases are being safely vented outside. Over time, electrical wear on the main control board or a buildup of debris in the fan can trigger this sudden stop.
Turn the main power switch to the boiler offWait for 30 secondsTurn the power back on to see if the fault clears
Your boiler is failing to light the flame, so it has purposefully shut down to prevent gas from escaping into your home.
Full guide for lockoutYour boiler has detected that it is getting too hot and has automatically switched itself off to prevent damage.
Full guide for Overheat cut-offYour boiler has failed to light the flame, so it has safely shut itself down to prevent any gas build-up.
Full guide for Ignition lockoutYour boiler is struggling to clear air fumes properly, so it has safely shut down to prevent any unsafe conditions.
Full guide for Air flow faulton the Worcester Bosch 24CDi BF
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 Worcester Bosch 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