How much does it cost to fix boiler error code 1-2-3?

Typical repair cost for the boiler 1-2-3 fault is £100-£350 including labour.

1-2-3 Medium

Boiler Fault Code 1-2-3

Also written as 123 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code 1-2-3 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 general issue that needs checking to prevent a full breakdown. (As reported on Remeha Gas 350)

Pick your boiler brand for the 1-2-3 fix

Remeha 1-2-3 1 model

Source

Information for the 1-2-3 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