BoilerFaultCodesTechnical description
Problem with fan/flue. Re-set as described for code 01.
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that the fan isn't moving enough air to safely expel exhaust gases through the flue. The most common reasons are a failing fan motor, a blockage in the flue pipe, or a build-up of debris in the small plastic tubes that monitor air pressure. Because the boiler cannot guarantee that harmful fumes are being moved outside, it shuts down as a critical safety precaution.
This fault can be more frequent during periods of heavy wind or extreme cold, as high gusts can disrupt the air pressure balance and ice can block the flue terminal.
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.