Indoor and Outdoor Unit Communication Error
What it means
This code appears on Gree split air conditioners when the indoor unit does not receive a valid signal from the outdoor unit, or the other way round. The outdoor unit stops so there is no cooling, while the indoor fan may keep running. On inverter models it also shows when the outdoor board does not power up at all. The same code can mean something else on other brands.
Models covered: Gree split (wall-mounted) air conditioners, mainly inverter models; the code shows on the indoor unit display. Older non-inverter models may show fewer codes.
Symptoms3
- The outdoor unit does not run at all while the indoor fan runs.
- The code appears immediately or a few minutes after start.
- It may appear after a new installation, relocation, a storm or a power cut.
Possible causes6
- Loose or corroded terminals of the interconnecting cable in either unit.
- Wrong wire order between the units after installation or relocation.
- Damaged interconnecting cable from rodents, heat or water.
- No power reaching the outdoor unit: a separate breaker off or a blown fuse on the outdoor board.
- Faulty outdoor or indoor control board or its communication circuit.
- Electrical interference where the signal cable runs with other power cables.
How to diagnose5
- Switch off at the breaker for a few minutes, then restart.
- Make sure the outdoor unit breaker, if separate, is on.
- The technician checks the terminals in both units and compares the wire order with the wiring diagram on the unit.
- The technician confirms voltage reaches the outdoor unit and checks the outdoor board fuse and indicator lights.
- The technician tests the cable continuity, then identifies which board is at fault.
How to fix5
- Tighten terminals, clean corrosion and correct the wire order to the diagram.
- Replace a damaged interconnecting cable with the correct size.
- Separate the signal cable from other power cables or use a suitable cable.
- Replace the fuse or the faulty outdoor or indoor board through a qualified technician.
- Run the unit and confirm the outdoor unit starts and the code does not return.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
In the Saudi market: SAR 100–2,500 (≈ USD 27–667)
Our prices come from the Saudi market, converted at a fixed rate (SAR 3.75 per USD). Prices in your country may differ a lot, so we show the cost level.
Most cases are a terminal or cable repair at low cost; replacing the outdoor inverter board is what raises the cost.
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
Why did E6 appear after moving the AC?
Usually the wire order between the units changed or a terminal was not tightened. Compare the connection with the diagram on the unit.
Does E6 always mean a bad board?
No. Wiring and terminals are far more common. Replace a board only after confirming power reaches it and the cable is sound.
Can I check the terminals myself?
Switch off the breaker first; the outdoor inverter board keeps a dangerous charge after switch-off. Opening the outdoor unit is best left to a technician.
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