BoilerFaultCodesThis light simply indicates that the boiler is receiving power and is switched on at the wall or spur.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: MAINS ON
What causes this fault?
This is not actually a fault, but a status indicator showing that the boiler is successfully receiving electrical power from your home's mains supply. It confirms that the external fused spur or plug is switched on and that the internal control board is active. You will see this light whenever the boiler is ready to operate or is currently heating your home.
DIY fix possible
No action required as this is a status indicator, not a faultIf the boiler is not firing despite this light being on, check that your thermostat is turned upEnsure your programmer is set to 'ON' or 'AUTO'
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A boiler cover plan would cover faults like NEON1 — no call-out fees, no surprises.
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