Daikin Mini Split Error Code P4: How to Fix It

Medium 30-60 minutes Medium Severity Verified June 2026
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Error Code
P4
Brand
Daikin
Product Type
mini_split
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Error code P4 on a Daikin mini split indicates a fault with the radiation fin temperature sensor. This sensor monitors the temperature of the outdoor unit's heat exchanger fins. When it fails or sends an abnormal reading, the system stops to prevent damage.
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Tools You'll Need

How to Fix Error Code P4

  1. Turn Off Power

    Always disconnect power before servicing the unit to avoid electric shock.

  2. Access the Outdoor Unit

  3. Locate the Radiation Fin Temperature Sensor

  4. Inspect Sensor Wiring and Connection

  5. Test the Sensor Resistance

  6. Replace If Faulty

    Ensure the replacement matches the specifications of the original sensor.

  7. Restore Power and Test

Parts You May Need

Radiation fin temperature sensor (thermistor)
Check Price on Amazon
Radiation fin temperature sensor (thermistor)
Check Price on Amazon
Radiation fin temperature sensor (thermistor)
Check Price on Amazon
Radiation fin temperature sensor (thermistor)
Check Price on Amazon
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When to Call a Professional

If the sensor resistance is normal and wiring is intact, the issue may be a faulty control board. This requires an HVAC technician to diagnose and replace the board.

Frequently Asked Questions

What does Daikin error P4 mean?
Error P4 indicates a radiation fin temperature sensor fault in the outdoor unit. The sensor is likely defective or has a wiring issue.
Can I still use my Daikin mini split with error P4?
No, the system will shut down to protect components. You must fix the sensor issue before resuming normal operation.
How much does it cost to fix Daikin error P4?
If you DIY, a replacement sensor costs $10–$20. Professional repair including labor may range from $100–$300.
Where is the radiation fin temperature sensor located?
It is on the outdoor unit's heat exchanger fins, usually near the top or middle. Look for a small wire with a clip or plug.
Can a dirty outdoor coil cause error P4?
While a dirty coil can cause overheating, it typically does not trigger a sensor fault. The error points to a sensor problem, not air flow.

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