Boiler Fault Code F.93

Also written as F93 — same fault.

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

Fault code F.93 appears across 2 boiler brands and 4 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is having a communication breakdown between its internal computer systems, which means it will stop providing heating and hot water until the connection is restored. (As reported on Viessmann Vitodens 100-W WB1A)