BoilerFaultCodes 79:0 Medium
Boiler Fault Code 79:0
Also written as 790 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 79:0 appears across 1 boiler brand and 5 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler's internal control panel is having a communication error and is struggling to coordinate with other linked components in the system. (As reported on Viessmann Vitodens 200)
Pick your boiler brand for the 79:0 fix
Source
Information for the 79:0 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