How much does it cost to fix boiler error code 4U?

Typical repair cost for the boiler 4U fault is £90-160 including labour.

4U High

Boiler Fault Code 4U

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code 4U 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 has stopped working because an internal temperature sensor has developed an electrical fault and can no longer read the heat levels correctly. (As reported on Ideal Maximiser SE)

Pick your boiler brand for the 4U fix

Ideal 4U 1 model

Source

Information for the 4U 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