BoilerFaultCodesYour boiler's main control board has lost connection with its internal components or the external thermostat, meaning it cannot receive the instructions it needs to run.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Break in communication.
What causes this fault?
This fault occurs when the boiler's internal computer can no longer 'talk' to the sensors or the thermostat that tells it when to turn on. The most common reason is a loose or damaged wiring connection inside the unit, or a internal failure on the main circuit board itself. This break in communication means the boiler enters a safety mode because it cannot guarantee it is receiving the correct operating instructions.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like A8 — 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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