High Lockout
Fault 02 / 43 on Worcester Bosch Greenstar CDi Compact

Your boiler's main control unit is confused because a small internal configuration plug has moved or is failing, causing the system to lock out 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

Internal fault: Coding switch position has been changed since initialisation phase.

What causes this fault?

This fault occurs when the boiler's main control board loses its unique identity because the small internal configuration chip has either come loose or failed. It is usually caused by physical vibrations over time or electrical interference preventing the board from reading the chip correctly. Because the boiler is no longer sure of its specific model and settings, it shuts down as a vital safety precaution.

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

EAView →C6View →

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