How much does it cost to fix boiler error code Return Thermistor Fault?

Typical repair cost for the boiler Return Thermistor Fault fault is £110-180 including labour.

Return Thermistor Fault High

Boiler Fault Code Return Thermistor Fault

Also written as RETURNTHERMISTORFAULT — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code Return Thermistor Fault appears across 2 boiler brands and 6 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 monitor the temperature of the water returning from your radiators, which prevents it from heating your home or water efficiently. (As reported on Ideal Logic Code Combi ESP1)

Pick your boiler brand for the Return Thermistor Fault fix

Ideal Return Thermistor Fault 5 models Johnson Starley Return Thermistor Fault 1 model

Source

Information for the Return Thermistor Fault 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