BoilerFaultCodesYour boiler's internal computer memory chip is not being detected, which has caused the system to shut down 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 boiler's main control board loses communication with a small memory chip called a code plug, which contains the boiler's essential operating software. The most common reason is a loose connection between the two components, though it can also be caused by a complete electronic failure of the chip or the circuit 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.
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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 25i (ZWB 7-25) 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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