FLASH OFF FLASH High

Main FLASH OFF FLASH Fault Code

Also written as FLASHOFFFLASH — same fault.

The Main FLASH OFF FLASH fault code means: your boiler has stopped working because the electricity supply reaching it is too low to run the internal components safely.. It appears on 1 Main model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Voltage less than 180V
Typical repair cost £100-350 (including labour)

DIY fix possible

Check if there is a regional power cut or if other appliances in your home are flickering.Ensure the boiler's fused spur switch is fully turned on and the plug is pushed in properly.If you use a prepaid electric meter, check that you have sufficient credit remaining.

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Main models that show the FLASH OFF FLASH fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Main FLASH OFF FLASH fault code information on this page is sourced and cross-checked against the official Main service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026