BoilerFaultCodesYour boiler is unable to control the gas flow properly, which is preventing it from lighting to provide heating or hot water.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Stepper motor fault (gas valve)
What causes this fault?
This fault occurs when the boiler's internal computer is unable to communicate with the mechanical motor that regulates gas flow. The most common reason is that the motor inside the gas valve has seized or failed, but it can also be caused by a loose electrical connection or a fault on the main control board.
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 15 — no call-out fees, no surprises.
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