How much does it cost to fix boiler error code F65?

Typical repair cost for the boiler F65 fault is £250-450 including labour.

F65 High

Boiler Fault Code F65

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 31 August 2026

Fault code F65 appears across 3 boiler brands and 20 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's internal computer boards are having trouble communicating with each other, preventing the system from starting up. (As reported on Glow-worm Ultracom 35 Store)

Pick your boiler brand for the F65 fix

Ferroli F65 1 model Glow-worm F65 12 models Heatline F65 7 models

Source

Information for the F65 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