Room Temperature Sensor Error

What it means

This code appears on Fujitsu General split and ducted units on the wired remote or indoor display; older models show it as a number of indicator lamp blinks instead of a number. It means the board reads an impossible value from the room temperature sensor, which points to an open or shorted circuit; this sensor measures the room air so the unit knows when to slow down or stop the compressor. Depending on the model, the unit stops or runs with limited control until the fault is repaired. The same number can mean something different on other brands.

Models covered: Fujitsu General (Fujitsu, O General) split and ducted units that show a two-digit error code on the wired remote or indoor display; older models show errors as lamp blink counts instead.

Related codes: 427473

Symptoms4

• Cooling stops or weakens and the code shows or the indicator lamps blink.
• The unit runs briefly and then stops.
• The unit does not return to normal after a restart.
• The indoor fan may keep running without cooling.

Possible causes5

• A loose or unplugged room temperature sensor connector on the board.
• A failed room temperature sensor whose resistance no longer matches the manufacturer table.
• A cut or chafed sensor wire from heat, rubbing or rodents.
• Moisture or corrosion at the connector from condensation in the indoor unit.
• A fault in the sensor input circuit on the board (less common).

How to diagnose5

1. Switch off at the breaker for a few minutes, restart and see whether the code returns.
2. Switch off the power before any check inside the indoor unit.
3. The technician inspects the sensor near the indoor air intake, its wire and its connector on the board.
4. The technician measures the sensor resistance at the current temperature and compares it with the manufacturer table.
5. If the sensor and wire are good, the technician checks the input circuit on the board.

How to fix5

1. Restart the unit after a power-off; a one-off glitch may clear.
2. Reseat the sensor connector and clean its pins.
3. Repair or replace a damaged sensor wire.
4. Replace the room temperature sensor with a part that matches the model.
5. Repair or replace the board if the input circuit is faulty, then run the unit and confirm the code does not return.

Repair cost

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

The cost stays low when reseating the connector or replacing the sensor fixes it, and rises when the board has to be replaced.

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