BoilerFaultCodesWhat the manual says
Manufacturer manualCentral heating return NTC fault
From this model's manual
Verified against the Vaillant Ecomax Pro 28e installation & service manual, page 26.
What causes this fault?
This fault occurs when the boiler's internal computer loses communication with the sensor that measures the temperature of the water coming back from your radiators. The most common reason is that the sensor itself has developed an electrical failure, or the wiring connecting it to the main control board has become loose or damaged.
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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