High Lockout
9U233 on Worcester Bosch GB162

Your boiler's computer or its security identity chip has failed, meaning the system cannot safely start the burner.

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

The burner control unit or KIM (boiler identification module) is faulty

What causes this fault?

This fault occurs when the boiler's central brain and its unique security identity chip stop communicating or fail internally. It usually happens due to a physical electrical failure within the circuit board's memory components or a loose connection where the identification module plugs in.

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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