BoilerFaultCodesYour boiler's main control unit is confused because a small internal configuration plug has moved or is failing, causing the system to lock out 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: Internal fault: Coding switch position has been changed since initialisation phase.
What causes this fault?
This fault occurs when the boiler's main control board loses its unique identity because the small internal configuration chip has either come loose or failed. It is usually caused by physical vibrations over time or electrical interference preventing the board from reading the chip correctly. Because the boiler is no longer sure of its specific model and settings, it shuts down as a vital safety precaution.
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 Fault 02 / 43 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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