BoilerFaultCodesYour boiler’s internal computer chip has lost connection with the main control board, meaning the system cannot identify which model it is and has stopped working for safety.
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 identification chip, which acts like the boiler's memory, becomes loose or develops a communication failure with the main circuit board. The most common reason is a physical vibration that has eased the chip out of its socket, or a component failure within the chip or the control board itself.
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 B1 — no call-out fees, no surprises.
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Worcester Bosch CDi Classic is discontinued — time for a new one?
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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