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C4-00

C4-00 — Heat exchanger temperature sensor problem

Daikin · ASHP Error Codes

What does C4-00 mean?

There is an issue with the temperature sensor located in the heat exchanger.

Common Causes

  • Damaged sensor
  • Loose wiring
  • Incorrect placement of the sensor

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the wiring harness connected to the heat exchanger sensor.

  2. 2

    Ensure the sensor is properly seated.

  3. 3

    Power off the unit for 1 minute, then power back on.

  4. 4

    A technician should verify sensor readings.

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

Related Faults

7H-017H-01 — Water flow problem7H-047H-04 — Water flow problem during domestic hot water production7H-057H-05 — Water flow problem during heating/sampling
Source: Daikin ASHP Error Codes
Open Manual (Page 2)Search more codes in this manual