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Verified boiler fault-code guides
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Worcester Bosch · Greenstar i System ErP
- Worcester Bosch EAThe manual associates the EA fault with no or low gas supply, a blocked condensate outlet, or a blocked flue outlet.
- Worcester Bosch A1 281Pump stuck or running dry.
- Worcester Bosch E2Flow temperature sensor shorted or disconnected (cause 222/223/350/351).
- Worcester Bosch D4 341Primary flow temperatures rising too fast.
- Worcester Bosch E9 276Primary flow temperature exceeded 95 °C.
- Worcester Bosch FDElectrical interruption — power interrupted during a lockout (Fd 231).
- Worcester Bosch 9UInternal error — control box or HCM defective or loose (9U 233).
- Worcester Bosch CC 800Outdoor sensor defect (only when an outdoor sensor accessory is fitted).
- Worcester Bosch H03Planned maintenance required — set burner-hours service interval expired.
- Worcester Bosch H13Service due — set maintenance interval (months) expired.
- Worcester Bosch H12Hot water cylinder (storage) sensor defect.
- Worcester Bosch H09Maintenance code: communication to the pump has failed.
- Worcester Bosch H29Maintenance code: outdoor sensor defect (only when an outdoor sensor accessory is fitted).
- Worcester Bosch H08Maintenance code: the set service date has expired and maintenance is required.
- Worcester Bosch b7Internal error: control box or HCM defective (cause 257).
- Worcester Bosch F1Internal error: control box or HCM defective (cause 259/263).
- Worcester Bosch A8HCM invalid: the fitted HCM does not match the control box or display type (cause 361).
- Worcester Bosch EHInternal error: control box or HCM defective (cause 258).
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