BoilerFaultCodesThe 6 most common faults
01
LOCKOUT High Engineer
Your boiler has stopped working because it failed to light or stay lit, and it needs a professional to investigate why it cannot maintain a stable flame.
Full guide for LOCKOUT02
Intermittent lockout High Engineer
Your boiler is struggling to stay lit because it cannot reliably sense the flame or is being affected by outside wind, causing it to turn itself off for safety.
Full guide for Intermittent lockout03
Burner motor fails to operate High Engineer
Your boiler has stopped working because the mechanical fan that pushes air for the combustion process is failing to turn on.
Full guide for Burner motor fails to operate04
Flame detection fault High Engineer
Your boiler is failing to light because the sensor that checks for a flame is unable to see one clearly.
Full guide for Flame detection fault05
No oil from nozzle High Engineer
Your boiler has stopped working because it is not receiving the oil supply it needs to create a flame.
Full guide for No oil from nozzle06
Ignition failure High Engineer
Your boiler is trying to start but cannot spark correctly to light the flame, which prevents it from providing any heating or hot water.
Full guide for Ignition failureon the Worcester Bosch Greenstar Utility
Ignition electrodeFlame rectification probeOil pumpControl boxPCBFlue 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