BoilerFaultCodesYour boiler has detected that the electricity supply coming into your home is at a lower voltage than it needs to operate safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Low mains voltage
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the incoming electrical voltage from your mains supply has dropped below the minimum level required for the components to function. Most commonly, this is caused by a temporary fluctuation in the local power grid, though it can also indicate a failing printed circuit board (PCB) that can no longer process power correctly.
This fault is slightly more common during internal cold snaps or heatwaves when the national grid experiences high demand, potentially leading to 'brownouts' or voltage drops.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like F7 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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