Low
4-b6 on Worcester Bosch Greenstar 2000

Your boiler has detected that the internal water temperature is very low and has activated its built-in frost protection mode to prevent freezing.

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.

Technical description

Temperature value for the system frost protection: 0...5...10 °C.

DIY fix possible

Ensure the boiler's electrical power remains switched onCheck that the room thermostat or programmer is calling for heatAllow the boiler to run its automatic anti-freeze cycle until the temperature risesEnsure any external pipework is properly insulated with lagging

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