Indoor unit will not operate, display shows E0 shortly after power-on

Safety first: Turn off the breaker to the indoor unit and verify power is off before removing any covers. Electronic boards can be damaged by static and live voltage.

• Power reset: Turn off the indoor unit breaker for at least 5 minutes, then restore power and try operating the unit again. Sometimes transient memory errors clear with a full reset.
• Inspect indoor PCB connections: Remove the front cover and access the control box. Check all low-voltage connectors on the indoor main PCB, especially any small 4–8 pin connectors leading to the EEPROM chip. Reseat connectors firmly.
• Look for visible PCB damage: Check for burn marks, swollen capacitors, or corrosion on the indoor PCB. If present, the board is likely defective and must be replaced.
• Do not attempt EEPROM reprogramming: Fujitsu EEPROMs require factory programming. If E0 persists after reset and connector checks, the indoor PCB assembly (with EEPROM) typically must be replaced.
• When to call a technician: If you are not comfortable working around electronics or if the unit is under warranty, contact an authorized Fujitsu service center to replace and program the indoor PCB.