Medium
d.73 on Vaillant ecoMAX 622

Your boiler is struggling to accurately measure or maintain the temperature of the water used for your taps.

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

Difference between warm start and hot-water outlet target value

Engineer required

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

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