How much does it cost to fix boiler error code 6.i?

Typical repair cost for the boiler 6.i fault is £120-250 including labour.

6.i High

Boiler Fault Code 6.i

Also written as 6I — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code 6.i 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 has stopped heating because it is not detecting enough water flowing through the system, which is a safety mechanism to prevent it from overheating. (As reported on Chaffoteaux Celtic 2 24 Rsc)

Pick your boiler brand for the 6.i fix

Chaffoteaux 6.i 3 models

Source

Information for the 6.i 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