High
internal error on Worcester Bosch Greenstar i

Your boiler's internal computer brain is having trouble communicating with its power supply, preventing the system from starting up.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Transformer. All connections to control board. Otherwise replace control board.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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