Group 1, 1 flash High

Boiler Fault Code Group 1, 1 flash

Also written as GROUP11FLASH — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code Group 1, 1 flash appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is failing to light the flame, which means it cannot produce any heating or hot water for your home. (As reported on Worcester Bosch Greenstar CDi Compact)

Pick your boiler brand for the Group 1, 1 flash fix

Worcester Bosch Group 1, 1 flash 1 model

Source

Information for the Group 1, 1 flash fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026