BoilerFaultCodesYour boiler has detected that the electricity supply coming into your home is unstable or vibrating at the wrong frequency.
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: Irregular mains frequency – possible electric supply problem – the electrical system needs checking
What causes this fault?
This fault occurs when the boiler's internal computer detects that the incoming electrical current is not at the steady 50Hz frequency required for safe operation. The most common reason is a temporary instability in the local power grid or a failing component on the boiler's circuit board that can no longer process the electricity correctly.
This fault can sometimes be more common during stormy weather or heavy periods of electrical grid instability, but it is not strictly tied to a specific season.
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 F34 — no call-out fees, no surprises.
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