BoilerFaultCodesTechnical description
Fan running when it should be off
What causes this fault?
This fault occurs when the boiler's internal safety sensor detects that the fan isn't moving enough air to safely vent exhaust gases. The most common reason is a buildup of dirt in the fan or a blockage in the small tubes that monitor air pressure, which prevents the boiler from clearing the path for ignition. In some cases, it can also be triggered by a failing fan motor or an electrical fault in the pressure sensor itself.
This fault is slightly more common during autumn and winter, as strong winds can occasionally cause pressure fluctuations in the flue, or spiders may crawl into the pressure tubes during the cooling months.
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.