BoilerFaultCodesTechnical description
Accessory Module is blocking burner operation
What causes this fault?
This fault occurs when an external control device or a specialized plug-in module sends a signal that overrides the boiler's ability to start. It usually happens because a component like a programmer or zone control unit has developed a communication error or has detected a safety issue that requires the burner to stay off. In some cases, a loose connection or moisture in the wiring between these external parts and the boiler is the primary trigger.
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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