BoilerFaultCodesYour boiler has detected a blockage or a fault in the system that drains away excess condensation, which has caused it to stop running 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: Problem exists with the condense sensor.
What causes this fault?
This fault occurs when the boiler's internal sensor detects that waste liquid, known as condensate, is not draining away correctly from the unit. The most common reason is a physical blockage in the trap or the internal pipework, which triggers a safety shut-off to prevent water from backing up into the combustion chamber. In some cases, the sensor itself may have failed or become corroded, sending a false signal to the control board.
This fault is significantly more common during freezing winter temperatures, as the external drain pipe can freeze and cause liquid to back up into the boiler.
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 d2 — no call-out fees, no surprises.
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