BoilerFaultCodesKeston 3 bar Fault Code
Also written as 3BAR — same fault.
The Keston 3 bar fault code means: your boiler's internal water pressure is currently too high, which can put unnecessary strain on the system's components.. It appears on 1 Keston model in our database.
Technical description: CH max pressure
DIY fix possible
Locate a radiator in your home, preferably one upstairs.Place a cloth under the radiator's bleed valve and use a radiator key to open it slightly.Let a small amount of water out until the boiler pressure gauge drops back into the green zone (usually 1.0 to 1.5 bar).Close the valve tightly and check that the boiler fault has cleared.
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Keston models that show the 3 bar fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Keston 3 bar fault code information on this page is sourced and cross-checked against the official Keston service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026