BoilerFaultCodesTechnical description
Fault diagnostic (identified by flashing lights on facia). Cleared by removing fault and/or main switch off/on.
What causes this fault?
This fault occurs when the boiler's internal computer identifies a communication failure between vital components, most often involving the fan or the air pressure switch. It acts as a safety shutdown because the system cannot confirm that harmful exhaust gases are being safely vented outside. Over time, electrical wear on the main control board or a buildup of debris in the fan can trigger this sudden stop.
This issue often surfaces during the first cold snap of autumn when the fan and electronic components are forced to work harder after sitting idle throughout the summer.
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.