High Lockout
F0262 on Worcester Bosch CDi Classic

Your boiler's main internal computer or its configuration chip has developed a fault and can no longer communicate correctly with the rest of the system.

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

Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked

What causes this fault?

This fault occurs when the boiler's main control board loses its memory or fails to establish a secure handshake with the small identification chip plugged into it. It is often caused by an internal electrical short within the circuitry or a loose connection between the module and the main board. Essentially, the boiler has 'forgotten' its own settings and can no longer operate safely.

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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