Discharge Pipe Thermistor Abnormality

What it means

This code appears on Daikin split, ducted and cassette air conditioners and means the thermistor on the compressor discharge pipe is reading implausibly because of an open or short circuit. This sensor protects the compressor from overheating, so the unit stops until it is fixed. The same code can mean something else on other brands.

Models covered: Daikin split air conditioners and Daikin ducted/cassette (SkyAir) units, which share the same error code system; the code shows on the wired remote or via the wireless remote check function.

Related codes: F3H9J6P4

Symptoms3

• Code J3 appears and the compressor stops.
• The code may appear shortly after starting.
• No cooling until the cause is fixed.

Possible causes5

• A loose or corroded sensor connector on the outdoor board.
• A thermistor worn out by the hot discharge pipe or by age.
• A sensor wire touching a hot pipe, damaging its insulation or breaking it.
• The thermistor has come off the pipe.
• A faulty sensor input circuit on the board.

How to diagnose4

1. Switch the unit off at the breaker for a few minutes, then restart.
2. A technician inspects the sensor on the discharge pipe, its wire and connector after isolating power and discharging the board.
3. The technician measures the thermistor resistance against the Daikin table at a known temperature.
4. If the sensor is good and the code persists, the board's sensor input is checked.

How to fix5

1. Refit the sensor on the pipe and reseat its board connector.
2. Repair the damaged wire and route it away from hot pipes.
3. Replace the discharge thermistor, which on some models comes as part of a sensor set.
4. Replace the outdoor PCB if its sensor input is proven faulty.
5. Run the unit long enough and confirm the code does not return.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

The sensor and its wire are cheap repairs; the top of the range only applies when the outdoor board is the cause.

Prices are rough estimates including the part and the technician’s fee, and vary with brand, model and part source.
Prices last updated: September 2026

Frequently asked questions