How much does it cost to fix boiler error code 3 bar?

Typical repair cost for the boiler 3 bar fault is £90-150 including labour.

3 bar Medium

Boiler Fault Code 3 bar

Also written as 3BAR — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

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

Most common meaning Your boiler's internal water pressure is currently too high, which can put unnecessary strain on the system's components. (As reported on Keston R-sm 20 FB)

Pick your boiler brand for the 3 bar fix

Keston 3 bar 1 model Sime 3 bar 1 model

Source

Information for the 3 bar 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