BoilerFaultCodesYour boiler has lost its connection to an external safety device or a plug-in controller, causing it to stop running as a safety precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Jumper 8-9 not detected.
What causes this fault?
This fault occurs when the electrical bridge that completes the safety circuit between the boiler and its external controls is broken. It is usually caused by a loose connection in the wiring, a faulty plug-in wireless receiver, or the small link plug falling out of place. Because the boiler can no longer verify that it is safe to operate, it shuts down immediately to prevent uncontrolled heating.
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 d3 — no call-out fees, no surprises.
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Worcester Bosch Greenstar 25HE 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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