BoilerFaultCodesWhat the manual says
Manufacturer manualA 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 is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Avoid the next call-out bill
A cover plan would handle faults like d2: no call-out fees, no surprise bills.
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Related fault codes
All 11 fault codes on the Syntesi 25
Seeing a different code? Every code this model can display, in one place.