How much does it cost to fix boiler error code 9.ii?

Typical repair cost for the boiler 9.ii fault is £150-350 including labour.

9.ii High

Boiler Fault Code 9.ii

Also written as 9II — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code 9.ii appears across 1 boiler brand and 3 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is overheating because water is not flowing through it properly, which has caused it to automatically shut down as a safety precaution. (As reported on Chaffoteaux Sterling FF)

Pick your boiler brand for the 9.ii fix

Chaffoteaux 9.ii 3 models

Source

Information for the 9.ii 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