BoilerFaultCodesYour boiler has detected an issue with the stability of the electrical power supply coming into your home.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Electricity network frequency error – fluctuation in electricity frequency.
What causes this fault?
This fault occurs when the boiler's internal computer detects that the incoming electrical supply is not staying at a steady frequency. The most common reason is an unstable local power grid or interference from other high-powered appliances in your home that are distorting the electrical signal. If the power supply is consistent, it usually indicates that the boiler's main control board has become oversensitive or damaged and can no longer process the electricity correctly.
DIY fix possible
Turn the boiler off using the power button or at the fused spur switchWait for 60 secondsTurn the power back on and check if the code clears as the local grid stabilizes
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A boiler cover plan would cover faults like E40 — 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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