BoilerFaultCodesTechnical description
Loss of communication between gas valve and boiler printed circuit board (PCB) or fault in air/gas unit.
What causes this fault?
This fault occurs when the boiler's main control board can no longer send or receive signals from the gas valve assembly. It is usually caused by a loose connection in the internal wiring or a critical electronic failure within the gas valve itself, which prevents the system from safely managing the fuel flow. Without this constant communication link, the boiler enters a safety mode to ensure no unburned gas enters the system.
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.
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