Boiler Fault Code UU/5

Also written as UU5 — same fault.

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

Fault code UU/5 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 is displaying the current temperature of the hot water leaving the unit, which is usually an informative status update rather than a critical system failure. (As reported on Ariston Genus 27)