High
No light on Worcester Bosch Greenstar 12 Ri

Your boiler has completely lost power and will not turn on at all, meaning you currently have no 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

Permanent mains supply to boiler. Boiler mains switch on. Fuse F1. Transformer (both coils below 100Ω). Otherwise replace control board (if boiler does not operate correctly).

From this model's manual
Verified against the Worcester Bosch/Worcester Bosch 12ri 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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All 5 fault codes on the Greenstar 12 Ri

Seeing a different code? Every code this model can display, in one place.

2 pulses5 pulsesFast flashFlue pressure switch

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