BoilerFaultCodesYour boiler is unable to light because the small nozzle that delivers gas to the main burner has become clogged with debris.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Blocked main burner injector
What causes this fault?
This fault occurs when microscopic debris or carbon deposits build up inside the tiny hole that sprays gas into the main burner. Over time, these particles block the flow entirely, meaning the boiler can no longer create the flame needed to heat your water or radiators.
This fault is more common when you first turn the heating on in autumn, as debris can settle and harden within the burner components during the summer months of inactivity.
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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