BoilerFaultCodesYour boiler's computer and internal display screen are no longer communicating correctly because they haven't been configured to recognize each other.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Invalid device specific number (DSN)
What causes this fault?
This fault occurs when the boiler's main control board and front display panel are unable to talk to each other correctly. It typically happens after a repair where a new part was installed but not programmed with the specific identity code required to match your exact boiler model.
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 F.70 — 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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