High
Off / Off on Worcester Bosch Greenstar i Junior

Your boiler has lost all power and is completely unresponsive, meaning it is currently unable to 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.

What the manual says

Manufacturer manual

No power at control board. Possible causes: Permanent mains supply to boiler, Boiler mains switch, Fuse F1 (2.5A) or Fuse F3 (0.5A), Transformer (both coils below 100Ω), or replace control board.

From this model's manual
Verified against the Worcester Bosch Greenstar I Junior installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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