BoilerFaultCodes.com
S.42 High

Your boiler has stopped working because its internal safety system detected that wastewater cannot be pumped away or an add-on component is unresponsive.

Technical description: Response from accessory module or defective condensate pump is blocking burner operation
Typical repair cost: £120-280 (including labour)

DIY fix possible

Check if the external condensate pipe is frozen outside your homeInspect the condensate pump's power cable to ensure it is plugged inCarefully check if the wastewater pipe or drain is blocked

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