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C9

C9 - Malfunction of humidity sensor system (Indoor Unit)

Daikin · Simple Self Diagnosis by Malfunction Code | Daikin

What does C9 mean?

This code means there is a problem with the sensor that measures humidity levels inside the room.

Common Causes

  • Faulty humidity sensor
  • Sensor wiring issue
  • Dirt or debris on the sensor

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Turn off the power to the unit.

  2. 2

    Clean the area around the humidity sensor if accessible.

  3. 3

    Restore power and check the display.

  4. 4

    If the problem continues, contact a technician.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

6-06-0 - External protection device activated (Heat reclaim ventilator)6-16-1 - Malfunction of PCB (Heat reclaim ventilator)6-26-2 - Ozone density abnormal (Heat reclaim ventilator)
Source: Simple Self Diagnosis by Malfunction Code | Daikin
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