BoilerFaultCodesYour boiler's small pilot light is on, but the main burner cannot engage to actually heat your home because the fuel path is obstructed.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Main burner fails to light, pilot burning. Blocked main burner injector
What causes this fault?
This fault occurs when debris or soot builds up inside the tiny hole of the main burner injector, physically blocking the gas from reaching the burner. While the pilot light stays lit to prove there is a flame, the blockage prevents the main fire from starting, meaning the boiler cannot produce heat for your radiators or water. The most common reason is a buildup of carbon or microscopic dust particles over several years of operation.
This issue often comes to light during the first cold spell of autumn, as the burner is required to run for longer periods and at higher capacities after being mostly dormant over the summer.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A boiler cover plan would cover faults like C.(5) — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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