BoilerFaultCodesYour boiler has detected an internal wiring problem or a connection issue that is preventing it from running safely.
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 detects a mismatch or a break in the electrical wiring harness that connects the main components. The most common reason is that a wire has become loose, damaged, or was incorrectly connected during a previous repair, preventing the system from communicating safely. In some cases, it can also be caused by using an incorrect wiring loom that doesn't match the specific model of your boiler.
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 F.43 — no call-out fees, no surprises.
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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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