BoilerFaultCodesThe 6 most common faults
01
LOCKOUT High Engineer
Your boiler has stopped working because it failed to ignite safely and has shut itself down to prevent any hazards.
Full guide for LOCKOUT02
Intermittent lockout High Engineer
Your boiler is struggling to stay lit reliably, causing it to periodically shut down as a safety precaution against flame or flue issues.
Full guide for Intermittent lockout03
Burner motor fails to operate High Engineer
Your boiler's fan motor is not starting, which prevents the unit from firing up to provide your home with heating or hot water.
Full guide for Burner motor fails to operate04
Flame detection fault High Engineer
Your boiler is failing to light because the sensor that monitors the flame is either covered in soot or has stopped working correctly.
Full guide for Flame detection fault05
No oil from nozzle High Engineer
Your boiler has stopped working because fuel is failing to reach the internal burner, meaning you currently have no heating or hot water.
Full guide for No oil from nozzle06
Ignition failure High Engineer
Your boiler is failing to start because the internal sensor responsible for lighting the flame is misaligned and cannot spark.
Full guide for Ignition failureon the Worcester Bosch Utility
Ignition electrodeFlame rectification probePrinted Circuit BoardFuel pumpPCBFlue seals
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