ErrorCodeDoctor
Daikin Air Conditioner C4 error code
The C4 error means your Daikin air conditioner detected a fault with the liquid pipe thermistor for the indoor heat exchanger. This sensor monitors the temperature of the liquid refrigerant pipe. Contact a qualified technician to test and replace the thermistor.
Common causes
- Liquid pipe thermistor is defective
- Indoor unit PCB has malfunctioned
- Thermistor connector has a poor contact
How to fix it
-
1
Contact a qualified technician to test and replace the liquid pipe thermistor
Related Daikin Air Conditioner error codes
A0
An external protection device connected to the indoor unit has been activated
A1
A fault was detected in the indoor unit PCB (control board)
A3
The drain level control system has detected an abnormality — drain may be clogged
A5
Freeze-up protection (cooling) or high pressure control (heating) has activated — check the air filter
C4 error — frequently asked questions
What does the C4 error mean on a Daikin air conditioner?
The indoor unit liquid pipe thermistor has a fault
What causes the C4 error?
The C4 error is usually caused by: Liquid pipe thermistor is defective; Indoor unit PCB has malfunctioned; Thermistor connector has a poor contact.
Can I fix the C4 error myself?
This is rated a hard fix — it often requires tools, parts, or experience, and may be safer left to a professional technician.
How much does it cost to fix the C4 error?
Fixing the C4 error on a Daikin air conditioner typically costs $80–$250, depending on parts and whether you do it yourself or hire a technician.
Is it safe to keep using my air conditioner with the C4 error?
We'd recommend addressing the C4 error before continuing to use the air conditioner, since hard-rated issues often involve a real fault rather than a minor glitch.