Boiler Fault Code 73:7

Also written as 737 — same fault.

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

Fault code 73:7 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 has detected a communication error with its internal control system or a connected smart module, which may prevent it from managing your heating correctly. (As reported on Viessmann Vitodens 300-W)