BoilerFaultCodesWhat the manual says
Manufacturer manualCentral 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.
Avoid the next call-out bill
A cover plan would handle faults like H9: no call-out fees, no surprise bills.
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