Medium
dE on Viessmann Vitodens 333-F

Your boiler has lost connection to one of its internal temperature sensors, which means it cannot accurately monitor the heat for one of your heating zones.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Control mode without room influence - Heating circuit M2 room temperature sensor lead break

From this model's manual
Verified against the Viessmann Vitodens 333 F installation & service manual, page 96.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the boiler loses signal from the temperature sensor responsible for monitoring a specific heating zone. It is typically caused by a loose connection plug, damaged wiring, or a failed sensor component that can no longer send electrical data to the main control board.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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