BoilerFaultCodesYour boiler’s control board has lost its identity settings, meaning the internal computer no longer knows which specific model it is supposed to be operating.
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 internal computer experiences a data mismatch or memory loss regarding its own model settings. The most common reason is that a replacement part was installed without being programmed correctly, or a power surge has corrupted the software communication between the main control board and the display unit.
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 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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