How much does it cost to fix boiler error code 31.5?

Typical repair cost for the boiler 31.5 fault is £150-300 including labour.

31.5 High

Boiler Fault Code 31.5

Also written as 315 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code 31.5 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 detected a communication error between its main control board and the internal display unit, preventing it from operating correctly. (As reported on Grant Vortex)

Pick your boiler brand for the 31.5 fix

Grant 31.5 1 model

Source

Information for the 31.5 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