BoilerFaultCodesYour boiler is struggling to send the correct message to its gas supply valves, which usually means it cannot light safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Control signal for both gas valves
What causes this fault?
This fault occurs when there is a communication failure between the boiler's main brain and the gas valves that let fuel into the burner. It is typically caused by a shortcut in the wiring or a failing circuit board that can no longer send the steady electronic signal required to keep the gas supply open. Because the boiler cannot confirm the gas valves are operating correctly, it shuts down immediately as a safety precaution.
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 D.30 — 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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