Derby Air Conditioner Error Codes Error Codes Led Status E0 EEPROM parameter error E1 Indoor / outdoor units communication protection E2 Zero-crossing signal error E3 Fan speed out of control E5 Open or short circuit of outdoor temperature sensor (T4) E6 Open or short circuit of room (T1) or evaporator temperature sensor (T2) P0 Outdoor PCB protection P1 Over voltage or too low voltage protection P2 Temperature protection of compressor top. P4 Inverter compressor drive error Note: E4 & P3: Reserved function Diagnosis and Solution E0 (EEPROM parameter error) error diagnosis and solution Circuit or software error on indoor PCB ⇒ Replace indoor PCB E1 (indoor / outdoor units communication protection) error diagnosis and solution E2 (zero-crossing signal error) diagnosis and solution E3 (indoor fan speed out of control) diagnosis and solution Troubleshooting *Unit does not star: Power cut. Wait for power to be restored. Unit may have become unplugged. Chec...