BoilerFaultCodesYour boiler's computer brains have lost their identity settings, usually because a new part was installed without being correctly programmed.
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 code (DSN)
What causes this fault?
This fault occurs when the boiler's internal memory chips are unable to identify which model they are controlling. It most commonly happens after a power surge or when a technician installs a new control board but forgets to enter the unique software code that matches your specific boiler's power output.
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.
Gas Safe Register →Protect yourself from future repair bills
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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