BoilerFaultCodesYour boiler is receiving too little electricity from the mains supply to operate safely, causing it to shut down.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Power supply <170V
What causes this fault?
This fault occurs when the electrical voltage entering the boiler drops to a level so low that the internal components can no longer function. The most common reason is a problem with the local power grid or an issue with your home's electrical wiring, though a failing main control board can also misread the incoming power.
This fault is more common during extreme cold snaps or heatwaves when the national grid is under heavy strain, leading to temporary 'brownouts' or voltage fluctuations.
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.
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A boiler cover plan would cover faults like 17 — no call-out fees, no surprises.
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