81 High

Keston 81 Fault Code

The Keston 81 fault code means: your boiler has switched itself off because it has reached an unsafe temperature, likely due to low water pressure or trapped air in your heating system.. It appears on 2 Keston models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: OVERHEAT LOCKOUT - 1 FILL SYSTEM TO 1.0 BAR - 2 BLEED RADIATORS - 3 CHECK RADIATOR VALVES OPEN - 4 RESET BOILER - 5 CONTACT INSTALLER
Typical repair cost £0-180 (including labour)

DIY fix possible

Check the pressure gauge and top up the system to 1.0 bar using the filling loopBleed your radiators to remove any trapped airEnsure your radiator valves (TRVs) are turned on and openPress the reset button on the boiler control panel

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Keston models that show the 81 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Keston 81 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