How much does it cost to fix boiler error code YELLOW LED ON every 0.5-secs?

Typical repair cost for the boiler YELLOW LED ON every 0.5-secs fault is £0-80 including labour.

YELLOW LED ON every 0.5-secs Low

Boiler Fault Code YELLOW LED ON every 0.5-secs

Also written as YELLOWLEDONEVERY05SECS — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code YELLOW LED ON every 0.5-secs 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 is currently running in a special engineer-only testing mode used to check combustion levels, meaning it is not in its normal operating state. (As reported on Vokera Compact HE)

Pick your boiler brand for the YELLOW LED ON every 0.5-secs fix

Vokera YELLOW LED ON every 0.5-secs 1 model

Source

Information for the YELLOW LED ON every 0.5-secs 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