BoilerFaultCodesYour boiler’s control computer has lost its identity settings, meaning it no longer knows which specific model it is and has shut down as a safety precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Invalid product code (DSN)
What causes this fault?
This fault occurs when the boiler's internal memory loses the crucial identification code that tells it how to operate safely. The most common reason is a communication failure between the main control board and the display screen, often caused by a power surge or a failing electronic component.
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.
Affiliate links — we may earn a commission at no extra cost to you.
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.
Affiliate links — we may earn a commission at no extra cost to you.