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

Typical repair cost for the boiler ON every 0.5-secs (RED LED) fault is £120-300 including labour.

ON every 0.5-secs (RED LED) High

Boiler Fault Code ON every 0.5-secs (RED LED)

Also written as ONEVERY05SECSREDLED — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code ON every 0.5-secs (RED LED) 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 a critical internal safety fault and has locked itself down to prevent damage, meaning it will not provide any heating or hot water until a professional engineer repairs it. (As reported on Vokera Compact HE)

Pick your boiler brand for the ON every 0.5-secs (RED LED) fix

Vokera ON every 0.5-secs (RED LED) 1 model

Source

Information for the ON every 0.5-secs (RED LED) 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 7 July 2026