What the manual says
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From this model's manual
Verified against the Worcester Bosch/Worcester Bosch Greenstar 12i System installation & service manual.
DIY fix possible
Check your external thermostat or boiler programmer to ensure they are set to 'on' or calling for heat.Turn the heating temperature dial on the boiler front panel up to ensure it is set higher than the current room temperature.Check if any smart heating app linked to your system has put the boiler into an 'off' or 'away' mode.
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Related fault codes
All 65 fault codes on the Greenstar 27i System Compact ErP
Seeing a different code? Every code this model can display, in one place.