BoilerFaultCodesTechnical description
Air pressure switch made.
What causes this fault?
This fault occurs when the boiler's safety system detects that the air pressure switch is already closed before the fan has even started. It is usually caused by the internal switch being physically stuck or the small sensing tubes becoming blocked with debris or moisture. Because the boiler cannot confirm a fresh flow of air is starting from scratch, it stops the ignition process as a safety precaution.
This issue can be more frequent in autumn and winter, as increased moisture and condensation within the flue pipes can settle in the pressure tubes and cause the switch to malfunction.
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.