Technical description
Is there a spark at pilot burner? Check lead continuity and inspect electrode and lead for damage.
What causes this fault?
This fault occurs when the boiler's ignition system fails to create the small pilot flame required to safely light the main burner. The most common reasons are a worn-out spark electrode that can no longer produce a spark, or a tiny blockage in the pilot injector preventing gas from reaching the ignition point.
This issue often surfaces during the first cold spell of autumn when a boiler that has been idle over summer is suddenly asked to work hard, causing aging ignition components to finally fail.
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.