BoilerFaultCodesYour boiler has detected an internal electrical fault with the component that controls the gas supply, meaning it cannot safely ignite for 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: Gas valve relay error
What causes this fault?
This fault occurs when the boiler's main control board detects a communication failure or a physical defect in the relay that triggers the gas valve. Effectively, the brain of the boiler can no longer safely tell the gas valve to open or close, so it shuts down as a safety precaution. The most common reason is internal wear and tear on the printed circuit board's electrical components or a fault within the gas valve's solenoid.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like A04 — 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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