BoilerFaultCodesYour boiler is not receiving enough electrical power from your home's supply to operate correctly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Low supply voltage
What causes this fault?
This fault occurs when the electrical voltage being supplied to the boiler's control systems drops below a safe working level. The most common reason is an issue with your home's main electrical supply or a failing component inside the boiler, such as the printed circuit board, that can no longer process the incoming power correctly.
This fault can sometimes occur during periods of extreme cold when local power grids are under heavy strain, leading to temporary 'brownouts' or fluctuations in supply voltage.
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 F17 — no call-out fees, no surprises.
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