Boiler Fault Code 6x

Also written as 6X — same fault.

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

Fault code 6x appears across 1 boiler brand and 3 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has detected a fault with the temperature sensor that controls your hot water, meaning your water may not reach the correct temperature or might not heat up at all. (As reported on Vokera Linea HE)