BoilerFaultCodesYour boiler has detected an issue with the electrical power supply coming from the grid or your home's wiring, meaning the electricity frequency is incorrect for it 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: 50 Hz ERROR The mains frequency is not 50 Hz
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the incoming electrical supply is not stable enough to run the electronic components safely. The most common reasons are fluctuations in the National Grid supply or issues with your home’s electrical wiring, though it can also be triggered if the boiler’s main control board has developed a fault and is misreading the power signal.
This fault is more common during periods of extreme weather, such as heavy storms or heatwaves, which can put the local electrical grid under stress and cause supply instability.
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 E34 — 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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