How much does it cost to fix boiler error code E66?

Typical repair cost for the boiler E66 fault is £120-200 including labour.

E66 High

Boiler Fault Code E66

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code E66 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 has stopped working because it is unable to accurately measure the temperature of the water being sent to your radiators, causing it to shut down for safety. (As reported on Ariston Genus 24 MFFI)

Pick your boiler brand for the E66 fix

Ariston E66 3 models Main E66 1 model

Source

Information for the E66 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