BoilerFaultCodesDaikin 1 Fault Code
The Daikin 1 fault code means: your boiler has detected that the water inside is getting too hot because trapped air is blocking the flow and the circulation pump is not running properly.. It appears on 2 Daikin models in our database.
Technical description: Temperature too high - Air in installation. Purge the air from the boiler and CH installation. Pump is not running. Reset or replace the pump, see par. 8.2.10
DIY fix possible
Check your central heating pressure gauge to ensure it is at the correct level (usually around 1 to 1.5 bar).Bleed your radiators starting from the ground floor up to release any trapped air in the system.Check if the circulation pump is stuck and try resetting it, or consult your manual if the issue persists.
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Daikin models that show the 1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Daikin 1 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 31 August 2026