How much does it cost to fix boiler error code 308?

Typical repair cost for the boiler 308 fault is £150-300 including labour.

308 High

Boiler Fault Code 308

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code 308 appears across 2 boiler brands and 5 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 internal electrical connection failure that is preventing it from operating safely, which means it will stay locked out until a professional inspects the internal circuitry. (As reported on Navien NCM 1130HH)

Pick your boiler brand for the 308 fix

Navien 308 1 model Worcester Bosch 308 4 models

Source

Information for the 308 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 7 July 2026