Low
203 on Worcester Bosch Greenstar 12i System

Your boiler is currently in a temporary holding state and is waiting for a signal from your heating controls, such as your thermostat or programmer, to tell it to start.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

System stand by

From this model's manual
Verified against the Worcester Bosch Greenstar 12i System installation & service manual, page 63.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the 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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