BoilerFaultCodesWhat the manual says
Manufacturer manualFlow temperature sensor interruption
From this model's manual
Verified against the Vaillant Ecotec Plus 826 installation & service manual, page 48.
What causes this fault?
This fault occurs when the boiler's main control board loses the electrical signal from the sensor that monitors the heat of the water leaving the unit. It is usually caused by the sensor itself failing due to age, or damage to the internal wiring that prevents information from reaching the central 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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