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C4

C4 - Indoor coil sensor fault

Daikin · Air Conditioning

What does C4 mean?

The sensor measuring the temperature of the indoor coil has an open or short circuit.

Common Causes

  • Indoor coil sensor is open or short circuited.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the connection of the indoor coil sensor to the PCB.

  2. 2

    Inspect the sensor and its wiring for any visible damage.

  3. 3

    If the sensor or wiring is damaged, it will need replacement by a technician.

Browse all codes in this manual (79)
Verified technical data. Last updated: April 2026

Related Faults

A0A0 - External protection activeA1A1 - Indoor PCB failureA2A2 - Malfunction of freezing protection
Source: Daikin Air Conditioning
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