High
360 on Worcester Bosch Junior 28i

Your boiler's internal computer chips are not communicating correctly or don't match, preventing the system from starting up for safety.

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

Heat control module (HCM) invalid – the inserted HCM does not correspond with the control box

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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Related fault codes

200View →203View →

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