BoilerFaultCodesYour boiler has lost its internal identity chip and can no longer recognize its own settings or model type.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Code plug not detected.
What causes this fault?
This fault occurs when the small 'identity chip' known as the code plug becomes loose or fails electronically, meaning the boiler can no longer remember which model it is or what its safety settings should be. It is most commonly caused by a physical connection failure at the chip's socket or a breakdown of the internal circuitry on the main control board.
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 b1 — no call-out fees, no surprises.
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Worcester Bosch Greenstar 25 HE Combi is discontinued — time for a new one?
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