BoilerFaultCodesThe 6 most common faults
Your boiler has detected an internal computer memory error and needs to be reset or inspected by a professional.
Switch the boiler off using its main power switch or plug.Wait for approximately 60 seconds to allow the internal memory to fully clear.Turn the power back on and check if the fault code has cleared.
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 has encountered an internal computer error and needs a reset to try and clear the glitch.
Locate the Reset button on the boiler's front control panel.Press and hold the Reset button for three to five seconds.Wait a few minutes to see if the boiler restarts and the error clears.
Your boiler's main internal computer is failing to 'talk' properly to its control board, meaning it has temporarily stopped working for safety reasons.
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 detected an internal communication or sensor error that requires professional attention to resolve safely.
Full guide for b3on the Worcester Bosch Greenstar 24 (2014-2016)
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