How much does it cost to fix boiler error code 73?

Typical repair cost for the boiler 73 fault is £90-160 including labour.

73 Medium

Boiler Fault Code 73

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 31 August 2026

Fault code 73 appears across 4 boiler brands and 10 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 fault with the sensor that monitors the temperature of the solar collector, meaning it cannot accurately read how hot the system is. (As reported on ECA FELiS FL 50 HM)

Pick your boiler brand for the 73 fix

Alpha 73 4 models ECA 73 1 model Ideal 73 1 model Viessmann 73 4 models

Source

Information for the 73 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 31 August 2026