BoilerFaultCodesTechnical description
Control box or the heat control module (HCM) is defective – control box and connections need checking or HCM might not be inserted properly and need replacing
What causes this fault?
This fault occurs when there is a critical breakdown in communication between the boiler's main brain and its specific configuration chip. It is usually caused by the electronic components failing over time or a loose physical connection prevents the system from reading its own settings. Because the boiler can no longer confirm its identity or safely manage the burner, it shuts down as a precaution.
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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