BoilerFaultCodesYour boiler's main control panel has lost connection with the internal computer, meaning they can no longer talk to each other to operate the heating.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Communication MMI -ESYS lost
What causes this fault?
This fault occurs when the data link between the display screen and the boiler's main control board is broken. The most common reason is a loose internal wire or a component failure on one of the circuit boards, which prevents the two parts of the boiler from sending signals to each other. Because the control panel can no longer 'talk' to the engine, the unit shuts down for safety.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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