BoilerFaultCodesTechnical description
Pilot fails to light - Control knob not pressed fully down.
What causes this fault?
This fault occurs when the small flame responsible for lighting the main burner fails to stay lit or cannot be detected by the system. The most common reasons include a worn-out heat sensor called a thermocouple, a blocked pilot hole preventing gas flow, or a buildup of soot on the sparking component. Without this steady pilot flame, the boiler shuts down as a safety precaution to prevent unburnt gas from escaping.
This issue is more frequent in autumn when boilers are turned back on after being idle all summer, as dust and debris often settle in the pilot assembly during the warmer months.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.