Medium
1021 on Worcester Bosch Greenstar 27CDi

Your boiler is having trouble 'talking' to your hot water tank or internal sensor, which means it cannot accurately tell if your water is hot enough.

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

Cylinder charging or hot water temperature sensor faulty

Engineer required

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

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