Boiler shows E15; burner lights but then shuts down quickly (gas models)

Safety first: Isolate gas and power before opening the combustion chamber. Allow components to cool.

Steps to check:

• Check earthing: Ensure the boiler has a solid earth connection at the supply terminal. Poor earthing can affect flame detection.
• Clean burner: Remove the burner assembly and clean the ports with a soft brush to remove dust and debris. Do not enlarge the ports.
• Inspect flame sensor lead: Check the ionization electrode lead for damage or loose connections.
• Monitor gas supply: If other gas appliances show issues, there may be a supply pressure problem that the gas supplier must address.
• Reassemble and test: After cleaning and checking connections, reassemble and test. If E15 persists, professional combustion analysis is required.

When to call a technician: Persistent flame loss requires a gas-safe technician to check pressures and combustion quality.