High Lockout
No light on Worcester Bosch Greenstar 12Ri

Your boiler appears to have no power and the display is completely dead, meaning it cannot provide any heating or hot water.

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

No power at control board. Possible solutions/checks: Permanent mains supply to boiler, Boiler mains switch ON, Fuse F1 - 2A Slow blow, Fuse F2 - 1.25A Anti-surge, Transformer (both coils below 100Ω. Otherwise replace control board.

What causes this fault?

This fault occurs when the electrical circuit inside the boiler is interrupted, preventing power from reaching the internal components. The most common reason is a blown internal fuse or a failure within the transformer, which acts as the heart of the boiler's electrical system. In some cases, a power surge or a short circuit on the main control board can cause the unit to shut down completely to prevent further damage.

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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