BoilerFaultCodesYour boiler’s main computer chip has forgotten its settings or has developed an internal electrical failure, meaning the unit cannot function.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: PCB UNCONFIGURED OR FAULTY
What causes this fault?
This fault occurs when the boiler's main control board loses its identity or suffers an internal electrical memory failure. Essentially, the 'brain' of the unit has either corrupted its software settings or the physical circuitry has worn out, preventing it from safely controlling the heating process.
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 L9 — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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