BoilerFaultCodesYour boiler is not receiving enough electrical power from your home's supply to operate safely and has shut down as a result.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Supply voltage too low (< 170V).
What causes this fault?
This fault occurs when the electrical supply entering the boiler drops below a safe threshold, meaning there isn't enough power to run the internal sensitive components. The most common reason is an issue with your home's incoming mains electricity or a failing internal circuit board that can no longer process the voltage correctly.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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 F17 — no call-out fees, no surprises.
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