BoilerFaultCodesAriston E04 Fault Code
The Ariston E04 fault code means: your boiler is failing to light the gas burner after several attempts, meaning you will not have any heating or hot water until the issue is resolved.. It appears on 8 Ariston models in our database.
Technical description: if the boiler does not sense that the burner has lit, the error code E04 will appear on the display, should this error occur, the boiler will attempt to relight two more times (20 seconds between each attempt).
DIY fix possible
Check that your gas emergency control valve is in the 'on' positionIf you have a prepay gas meter, check that you have sufficient creditTry to reset the boiler by pressing the reset button for 5 secondsCheck if other gas appliances in your home, like a hob, are working correctly
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Gas Safe Register →Ariston models that show the E04 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ariston E04 fault code information on this page is sourced and cross-checked against the official Ariston service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026