BoilerFaultCodesTechnical description
Incorrect fan speed – external draught over the boiler or defective gas/air unit.
What causes this fault?
This fault occurs when the boiler's internal computer detects that the fan isn't spinning at the precise speed required to safely push exhaust gases out of the flue. The most common reason is a build-up of debris or mechanical wear within the fan motor, though it can also be triggered by strong winds blowing directly into the flue pipe from outside.
This error is more frequent during periods of extreme wind or stormy weather, as high air pressure pushing back into the flue can physically prevent the fan from reaching its target speed.
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.