BoilerFaultCodesWhat the manual says
Manufacturer manualFlow Thermistor Fault
From this model's manual
Verified against the Zanussi/Zanussi Ultra Plus Combi installation & service manual.
What causes this fault?
This fault occurs when the sensor responsible for measuring the heat of the water leaving your boiler fails to send a correct signal to the main control board. The most common reason is that the sensor has physically degraded or developed an electrical short, but it can also be caused by loose wiring or a glitch in the boiler's internal computer.
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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Related fault codes
All 38 fault codes on the Ultra Plus Combi
Seeing a different code? Every code this model can display, in one place.