How much does it cost to fix boiler error code E1-66?

Typical repair cost for the boiler E1-66 fault is £100-250 including labour.

E1-66 Medium

Boiler Fault Code E1-66

Also written as E166 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code E1-66 appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is struggling to automatically adjust its internal settings for the burner to stay lit and is attempting to restart itself. (As reported on Daikin D2CND)

Pick your boiler brand for the E1-66 fix

Daikin E1-66 1 model

Source

Information for the E1-66 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