BoilerFaultCodesWhat the manual says
Manufacturer manualMain board connection fault. Main board defective. Check connection and wires
Shared across the range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
What causes this fault?
This fault occurs when the boiler's main control centre can no longer send or receive signals from its internal components, causing the system to freeze up for safety. The most common reason is a physical breakdown of the circuitry on the main board or a loose connection in the wiring that links the components together.
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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