Worcester Bosch Greenstar Heatslave II Fault Codes

OilCombi Oil 12-32 kW 2015-present

GC Numbers: 47-440-4947-440-5047-440-51

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Most common fault codes

Code	Severity	Plain English	DIY
9F855	High	Your boiler has stopped working because it cannot light the burner, which most often happens when your oil tank is empty or there is an issue with the oil supply.	Yes
9F856	High	Your boiler has stopped working because it has been reset too many times while trying to clear a burner fault, and it has now locked itself for safety.	Engineer
218	High	Your boiler has likely experienced a glitch or internal hardware communication error within its main computer system.	Yes
Alert	High	Your boiler has detected an internal error and is waiting for you to look at the display to reveal the specific fault code causing the problem.	Engineer
E5	High	Your boiler has encountered an internal electronic communication error that is preventing it from running safely.	Yes
ECO	Low	Your boiler is simply in energy-saving mode, which means it will not pre-heat your hot water in order to save on fuel costs.	Yes

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