How much does it cost to fix boiler error code 517?

Typical repair cost for the boiler 517 fault is £150-350 including labour.

517 High

Boiler Fault Code 517

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code 517 appears across 1 boiler brand and 7 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 communication error between its main computer and the internal control system, causing it to stop working for safety reasons. (As reported on Navien NCB 28 HE)

Pick your boiler brand for the 517 fix

Navien 517 7 models

Source

Information for the 517 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