BoilerFaultCodesDaikin 81-01 Fault Code
Also written as 8101 — same fault.
The Daikin 81-01 fault code means: your boiler has detected an issue with the sensor that measures the temperature of the water leaving the unit, which usually results in the system shutting down for safety.. It appears on 1 Daikin model in our database.
Technical description: Flow temperature sensor error – try resetting the boiler
What causes the Daikin 81-01 fault?
This fault occurs when the boiler's internal computer stops receiving a reliable signal from the sensor that monitors the heat of the water leaving the unit. The most common reason is that the sensor has physically failed or developed a short circuit, but it can also be caused by loose or damaged wiring between the sensor and the main control board.
DIY fix possible
Locate the power button or reset switch on the boiler control panelPress and hold the reset button for five secondsWait for the boiler to restart and check if the error code clears
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Gas Safe Register →Daikin models that show the 81-01 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Daikin 81-01 fault code information on this page is sourced and cross-checked against the official Daikin service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026