Serial Communication Error (Indoor and Outdoor Units)

Home Appliance Error Codes Fujitsu Split AC

Can you still use it? With care until repaired

Who can fix it? Needs a technician

Typical repair time 30 minutes – 3 hours

Typical cost SAR 100 to 2,500

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 indoor and outdoor units are not exchanging communication signals properly over the interconnecting cable, so the compressor stops and the unit does not cool. 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.

Symptoms4

The indoor unit runs but the air is not cold.
The outdoor unit does not start or stops after a short time.
Code 11 is shown or the indicator lamps blink in a set pattern.
The code may appear after a power cut or a thunderstorm.

Possible causes5

Loose or corroded interconnecting cable terminals in one of the units.
No power to the outdoor unit because of a tripped breaker or a blown fuse on its board.
A damaged cable, or wires in the wrong order after installation or service.
Electrical noise from nearby power cables or an unstable supply.
A faulty outdoor or indoor board.

How to diagnose5

Switch off at the breaker for a few minutes, restart and see whether the code returns.
Make sure any outdoor breaker is on and the supply is stable.
With power off, the technician checks the cable terminals and wiring order against the manufacturer diagram.
The technician checks that supply and signal reach the outdoor unit and compares them with the manufacturer specification.
The technician checks the outdoor board fuse and diagnostic LEDs to find the faulty board.

How to fix5

Restart after a power-off; a brief voltage dip may have caused it.
Tighten and clean the cable terminals and correct the wiring order.
Replace a damaged cable and route it away from power cables where possible.
Replace the fuse or restore power to the outdoor unit.
Repair or replace the faulty board, then confirm the code does not return.

Repair cost

0–200

200–600

600–1,500

1,500+

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

The cost stays low for a loose terminal or damaged cable, and rises when the outdoor 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

My unit shows no numbers; how do I know it is code 11?

Older models show faults as indicator lamp blinks, and the model manual lists which blink pattern means a communication error.

Can a power cut cause this code?

It can appear after a power cut or voltage swing and clear on restart. If it stays, the wiring or a board is at fault.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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