Low
4-b1 on Worcester Bosch Greenstar 2000

Your boiler is simply indicating whether its internal weather-monitoring feature is currently turned on or off.

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

Device-internal weather-compensated control: OFF: not active, ON: active.

From this model's manual
Verified against the Worcester Bosch Greenstar 27cdi 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.

DIY fix possible

Locate the boiler's control panelNavigate to the secondary settings menuEnable or disable the 'Weather Compensation' setting based on your preference

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