BoilerFaultCodesWhat the manual says
Manufacturer manualMaximum difference between T1 and T2 exceeded
From this model's manual
Verified against the Ideal Maximiser Se installation & service manual.
What causes this fault?
This fault occurs when the boiler detects an unstable electrical signal or a sudden drop in voltage while it is firing. It is usually caused by a loose connection in the internal wiring, a failing control board, or an issue with the electrical circuit providing power to the unit.
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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