How much does it cost to fix boiler error code 2 04?

Typical repair cost for the boiler 2 04 fault is £120-220 including labour.

2 04 Low

Boiler Fault Code 2 04

Also written as 204 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code 2 04 appears across 3 boiler brands and 10 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is having trouble communicating with the solar panel sensor, meaning it cannot accurately monitor the temperature of your solar water heating system. (As reported on Ariston Clas HE R)

Pick your boiler brand for the 2 04 fix

Ariston 2 04 8 models Chaffoteaux 2 04 1 model Johnson Starley 2 04 1 model

Source

Information for the 2 04 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