Low Warning
dA on Viessmann Vitodens 333

Your boiler has lost its connection to the indoor thermostat sensor, meaning it can no longer adjust the heating based on the actual temperature inside your home.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description

Control mode without room influence - Room temperature sensor heating circuit A1 shorted out

What causes this fault?

This fault occurs when the communication link between your boiler and the indoor temperature sensor is broken. The most common cause is a physical failure of the sensor’s internal components or a loose connection in the wiring that tethers the sensor to the boiler’s main control board.

Engineer required

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

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