How much does it cost to fix boiler error code 1 flash red?

Typical repair cost for the boiler 1 flash red fault is £120-200 including labour.

1 flash red High

Boiler Fault Code 1 flash red

Also written as 1FLASHRED — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code 1 flash red appears across 3 boiler brands and 6 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 unable to accurately measure the temperature of the water flowing through it, likely due to a loose wire or a faulty sensor. (As reported on Potterton Apollo)

Pick your boiler brand for the 1 flash red fix

Baxi 1 flash red 4 models Main 1 flash red 1 model Potterton 1 flash red 1 model

Source

Information for the 1 flash red 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