BoilerFaultCodesYour boiler is failing to ignite the main gas flame, which means your heating and hot water will not work.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Check main burner injector, supply on terminals of main gas valve, or PCB connections
What causes this fault?
This fault occurs when the boiler's control system attempts to start the heating cycle but fails to establish a sustained flame at the main burner. The most common reasons include a blockage in the pilot assembly preventing the gas from reaching the burner or an electrical failure where the gas valve is not being told to open by the control board.
This issue is more frequent during the first cold spell of autumn when dust or debris accumulated over the summer can clog the burner injectors or pilot light.
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.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like Main burner does not light — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Ideal Classic SE9 RS is discontinued — time for a new one?
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.
Affiliate links — we may earn a commission at no extra cost to you.