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 voltage required for the boiler's sensitive electronics to function. While it is often caused by a temporary dip or brownout in the local power grid, it can also be triggered if the boiler's internal control board develops a fault and can no longer process the incoming power correctly.
This fault can be more common during periods of extreme cold or heatwaves when the national electricity grid is under high demand, leading to localized voltage drops.
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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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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