Medium
F.03 on Vaillant ecoTEC Plus 826

Your boiler is struggling to detect the temperature of your hot water cylinder, meaning it may not heat your water up correctly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Technical description

Cylindertemperature sensorinterruption

Engineer required

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

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