Mitsubishi Heavy Industries Error Codes Split Systems VRF Inverter Multi-System 1.Split Systems Whether a failure exists or not on the indoor unit and outdoor unit can be know by the contents of remote controller eroor code, indoor/outdoor unit green LED (power pilot lamp and microcomputer normality pilot lamp) or red LED (check pilot lamp). a.Check Indicator Table; Indoor Unit Side Error Codes Cause E1 When multiple remote controllers are used for control, the power supply to some indoor units is OFF. Indoor unit PCB fault The remote controller wire Y is open. The remote controller wires X and Y are reversely connected. Noise is penetrating the remote control lines. The remote controller or indoor control PCB is faulty. E5 Indoor / outdoor transmission error. Outdoor unit control PCB is faulty when the power is turned on, or the inverter parts are faulty. Outdoor unit microcomputer failure. E6 Indoor unit heat exchanger thermistor failure E7 Indoor unit return air thermistor fai...