BoilerFaultCodesYour boiler is not receiving enough electrical power from the grid to operate safely and has shut down as a precaution.
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 Contact electricity provider
What causes this fault?
This fault occurs when the electrical supply entering your home drops below the minimum level required for the boiler to function safely. The most common reason is an external issue with the local power grid, though it can also be caused by a faulty internal circuit board failing to process the incoming voltage correctly.
This fault can be more common during peak winter periods or extreme weather events when the national grid is under heavy load or power lines are damaged.
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 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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