HC-01 Low

Daikin HC-01 Fault Code

Also written as HC01 — same fault.

The Daikin HC-01 fault code means: your boiler has a fault with the thermometer that measures hot water temperature, meaning your hot water may be unreliable although your heating should still work.. It appears on 1 Daikin model in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Domestic hot water (DHW) temperature sensor error. The boiler will continue to operate but you need to Contact a heating engineer

What causes the Daikin HC-01 fault?

This fault occurs when the sensor responsible for monitoring the temperature of your tap water fails to send a consistent signal to the boiler's control board. The most common reason is that the internal thermistor has worn out over time or a small amount of corrosion has developed on the electrical connections. Without this data, the boiler cannot safely judge how hot to heat your water, leading to the error message.

Typical repair cost £90-160 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Daikin models that show the HC-01 fault code

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

Source

Daikin HC-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