BoilerFaultCodesThe 6 most common faults
Your boiler has detected that there is not enough water circulating through the system to operate safely.
Check your boiler's pressure gauge to see if it is below 1 barLocate the filling loop (usually silver braided hoses under the boiler)Slowly open the valves until the pressure reaches 1.5 bar, then close them tightly
Your boiler has shut down because it has detected that the water inside is Getting too hot, which is a safety feature to prevent damage.
Check if any radiator valves are closed and open them fullyEnsure your system pressure is between 1 and 1.5 bar on the gaugePress the 'Reset' button for five seconds to restart the boiler
Your boiler is failing to light the gas or isn't detecting that the flame has started, causing the system to shut down for safety.
Check if other gas appliances in your home, like a hob, are working to confirm your gas supply is active.If it is freezing outside, check that your external condensate pipe hasn't frozen and blocked.Press and hold the reset button for five seconds to see if the boiler restarts.
Your boiler's internal computer has lost contact with its control panel or external sensors, meaning it cannot receive the instructions it needs to work.
Full guide for A8Your boiler's computer memory chip is loose or missing, meaning the system doesn't know which model it is and has stopped working for safety.
Full guide for b1Your boiler has stopped working because the internal fan, which clears exhaust gases, isn't spinning fast enough to operate safely.
Full guide for C1on the Worcester Bosch R30 HE Plus
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