How much does it cost to fix boiler error code 8 yellow?

Typical repair cost for the boiler 8 yellow fault is £180-350 including labour.

8 yellow Emergency

Boiler Fault Code 8 yellow

Also written as 8YELLOW — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code 8 yellow 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 that the gas valve is opening at the wrong time or when it hasn't been told to, which is a safety concern that prevents the appliance from running. (As reported on Ferroli Combi 77 FF Popular)

Pick your boiler brand for the 8 yellow fix

Ferroli 8 yellow 1 model

Source

Information for the 8 yellow 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