BoilerFaultCodesYour boiler has stopped working because the system that removes waste water is blocked or the pump used to drain it has failed.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Condensate pump fault
What causes this fault?
This fault occurs when the safety system detects that the acidic water produced during the heating process cannot be drained away safely. The most common reasons are a physical blockage in the drainage pipes or a mechanical failure in the pump responsible for pushing that waste water out of the property.
This fault is significantly more common during freezing winter temperatures, as the external waste pipe can freeze solid and cause water to back up into the 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 F77 — no call-out fees, no surprises.
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