BoilerFaultCodesVokera A40 Fault Code
The Vokera A40 fault code means: your boiler has shut down because it has reached an unsafe temperature and needs to cool down before it can be reset.. It appears on 3 Vokera models in our database.
Technical description: Limit thermostat
DIY fix possible
Check that all radiator valves are fully open to allow water to circulate.Ensure there is enough water pressure in the system (typically 1.0 to 1.5 bar).Press the reset button or turn the mode selector to 'off/reset' and then back to 'on' once the boiler has cooled.
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Vokera models that show the A40 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera A40 fault code information on this page is sourced and cross-checked against the official Vokera service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026