BoilerFaultCodesThe 6 most common faults
01
BUBNEB STAYS ON High Engineer
Your boiler is failing to ignite properly because debris or trapped air is interfering with the gas or water flow, meaning your heating and hot water will not work.
Full guide for BUBNEB STAYS ON02
HEATING BODY NOISE High Engineer
Your boiler is making loud banging or kettling noises because of internal debris buildup, incorrect gas settings, or restricted water circulation.
Full guide for HEATING BODY NOISE03
PILOT FLAME DOES NOT LIGHT High Engineer
Your boiler is failing to ignite because it cannot start the small pilot flame required to trigger the main burner.
Full guide for PILOT FLAME DOES NOT LIGHT04
UNSTABLE FLAMES Emergency Engineer
Your boiler is struggling to keep a steady flame, which suggests either moisture is trapped in the gas supply or the system cannot breathe properly through its exhaust.
Full guide for UNSTABLE FLAMES05
POOR PILOT FLAME Emergency Engineer
The small pilot flame that acts as a signal to ignite your boiler is too weak or flickering, so the system is shutting down for safety to prevent gas from escaping unburnt.
Full guide for POOR PILOT FLAME06
EXPLOSIVE IGNITION Emergency Engineer
Your boiler is struggling to light smoothly, causing a small 'pop' or bang sound when it tries to start instead of igniting quietly.
Full guide for EXPLOSIVE IGNITIONon the Chaffoteaux Britony Duo 55
Gas valveWater section diaphragmSlow ignition deviceHeat exchangerPumpPilot injector
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 Chaffoteaux 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