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

Typical repair cost for the boiler Return Thermistor Fault fault is £110-190 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 31 August 2026

Fault code Return Thermistor Fault appears across 3 boiler brands and 14 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 an issue with a temperature sensor that monitors the water returning from your radiators, preventing the system from heating up safely. (As reported on Ideal Logic Max Heat 2)

Pick your boiler brand for the Return Thermistor Fault fix

Ideal Return Thermistor Fault 7 models Johnson Starley Return Thermistor Fault 2 models Keston Return Thermistor Fault 5 models

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 31 August 2026