BoilerFaultCodesYour boiler has stopped working because of a wiring issue or an electrical connection problem inside the main control panel.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Faulty cable loom | Faulty or incorrect loom fitted
What causes this fault?
This fault occurs when the boiler's internal computer stops receiving the correct electrical signals from the main wiring system. The most common reason is that the plastic connectors have vibrated loose over time or the wires themselves have developed a break or short circuit. Because the control board cannot safely communicate with the various parts of the boiler, it shuts down as a safety precaution.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like F.42 — no call-out fees, no surprises.
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Vaillant Thermocompact 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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