BoilerFaultCodesYour boiler is having trouble monitoring the temperature for your second heating zone, which may prevent that specific area of your home from warming up properly.
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: Central Heating Zone 2 Thermistor Fault
What causes this fault?
This fault occurs when the boiler's control board loses communication with the temperature sensor dedicated to your second heating area. The most common reason is that the sensor has failed internally or the electrical wiring connecting it to the main unit has become loose or damaged. Without this data, the boiler cannot safely judge how much heat to send to that specific part of your home.
This fault often becomes apparent during autumn when the heating is turned on for the first time after summer, as the sensor may have failed while the system was idle.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like H9 — no call-out fees, no surprises.
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