BoilerFaultCodesYour boiler has stopped working because the electrical power coming into your home is at a lower voltage than it needs 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: LOW MAINS VOLTAGE - CONTACT ELECTRICITY PROVIDER
What causes this fault?
This fault occurs when the electrical supply entering the boiler drops below 190 volts, which is too low for the internal components to function. While it is sometimes caused by a failing control board within the boiler, it most commonly originates from an issue with the National Grid supply or the electrical wiring leading to your home.
This fault is occasionally more frequent during winter or periods of extreme weather when the local electrical grid is under high demand or power lines are affected by storms.
DIY fix possible
Check if other appliances in your home are acting strangely or lights are flickeringContact your electricity network provider to report a potential power supply issueOnce the external power issue is resolved, reset the boiler using the 'RE' dial or button
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like F7 — 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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