How much does it cost to fix boiler error code Lights On Off Flash?

Typical repair cost for the boiler Lights On Off Flash fault is £80-150 including labour.

Lights On Off Flash Emergency

Boiler Fault Code Lights On Off Flash

Also written as LIGHTSONOFFFLASH — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code Lights On Off Flash appears across 2 boiler brands and 5 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 electrical wiring coming into the unit is connected backwards, which is a safety risk and prevents the system from starting. (As reported on Baxi Solo 3)

Pick your boiler brand for the Lights On Off Flash fix

Baxi Lights On Off Flash 2 models Potterton Lights On Off Flash 3 models

Source

Information for the Lights On Off Flash 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