BoilerFaultCodesYour boiler is not receiving enough electrical power from the main supply 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 – the voltage may be interrupted or inconsistent and needs checking
What causes this fault?
This fault occurs when the electrical supply entering the boiler drops below the minimum level required for the internal components to function correctly. The most common reason is an issue with the local power grid or a faulty internal circuit board that can no longer process the incoming voltage. In some cases, it can also be triggered by loose electrical connections or other high-drain appliances on the same circuit causing a temporary dip in power.
This fault can be more common during winter or extreme weather when the local power grid is under heavy strain, leading to 'brownouts' or fluctuating voltage levels.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like 356 — no call-out fees, no surprises.
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