High
9U 233 on Worcester Bosch Hideaway

Your boiler has lost its connection to its internal memory chip, meaning it cannot properly identify itself or control the heating process.

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) error – problem with code plug

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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