Note on VRF systems: a single VRF fault can be raised by any one of several indoor units sharing an outdoor unit. Always note which indoor unit’s controller first showed the code — it narrows the fault fast.
Safety first: burning smell, sparking, or a tripped breaker means a possible short circuit — cut power at the main board and call an electrician. Suspected gas leakage or refrigerant faults need a certified technician with proper equipment. See the full
disclaimer before acting on any code.
DK Daikin VRV › Code Likely meaning What to check U4 Transmission error between indoor and outdoor units Check shielded control wiring across all connected indoor units. E3 High pressure protection activated Outdoor coil blocked or airflow restricted around the outdoor unit. E4 Low pressure protection activated Possible refrigerant shortage — needs gauge check by a technician. E7 Outdoor fan motor error Check for obstruction or a failed outdoor fan motor. L4/L5 Outdoor unit inverter compressor overheat Check outdoor unit ventilation clearance and ambient temperature. P4 Discharge pipe thermistor abnormality Sensor fault at compressor discharge — technician required. A1 Indoor PCB defect Usually requires indoor board replacement. C4 Indoor heat exchanger sensor error Check the indoor coil sensor connection. C9 Indoor suction air sensor error Check the suction air sensor wiring. H8 Compressor current sensor error Outdoor unit fault — needs technician diagnosis.
MB Mitsubishi Electric › Code Likely meaning What to check P1 Indoor intake air sensor error Check the intake sensor wiring and connector. P6 Freeze/high-temperature protection Check filter cleanliness and refrigerant charge. U2 High discharge temperature / low refrigerant Possible leak — needs technician inspection. E6/E7 Communication error between indoor and outdoor unit Check the control wiring across the whole line. F1 Outdoor unit phase reversal or open phase Check the incoming power supply phasing. P8 Pipe (liquid) temperature sensor error Check the liquid pipe sensor connection. P9 Outdoor unit sensor error Check outdoor sensor wiring and connectors. E0 Remote controller signal reception error Check the remote controller and its wiring. E9 Indoor/outdoor unit communication mismatch Check control wiring across all connected indoor units. L3 Outdoor unit electrical box high temperature Check outdoor unit ventilation and electrical box cooling.
LG LG Multi V (VRF) › Code Likely meaning What to check CH 05 Communication error between indoor unit and outdoor VRF module Check the communication cable and its shielding across the line. CH 10 Central controller communication error Check wiring and address settings at the central controller. CH 41 High pressure protection on outdoor module Check outdoor coil cleanliness and airflow clearance. CH 43 Low pressure protection Possible refrigerant shortage — needs gauge check. CH 53 Outdoor unit address duplication or setting error Check outdoor module address/rotary switch settings. CH 38 High pressure sensor abnormal Check outdoor coil cleanliness and airflow clearance. CH 39 Low pressure sensor abnormal Possible refrigerant shortage — needs gauge check. CH 49 Outdoor unit fan motor error Check for obstruction or motor failure at the outdoor fan. CH 61 Power factor correction (PFC) circuit error Outdoor PCB fault — needs technician diagnosis. CH 65 Compressor overcurrent Check outdoor unit load and ventilation clearance.
TB Toshiba VRF / SMMS › Code Likely meaning What to check E03 Communication error between indoor and outdoor unit Inspect the shielded control cable run. E04 Duplicate indoor unit address Check indoor unit address settings on the DIP switches. E16 Capacity over — too many indoor units connected Check the total connected indoor capacity against the outdoor rating. F10 High pressure protection Outdoor coil blocked or ambient temperature too high. F23 Discharge temperature sensor error Sensor fault at compressor discharge — technician required. F29 Outdoor unit fan motor error Check for obstruction or motor failure at the outdoor fan. F31 Low pressure protection Possible refrigerant shortage — needs gauge check. E01 Remote controller communication error Check the remote controller wiring. E20 Indoor unit fan motor error Check for obstruction or a failed indoor fan motor. H01 Compressor overcurrent Check outdoor unit load and ventilation clearance.
HT Hitachi Set Free (VRF) › Code Likely meaning What to check 03 Communication error between indoor and outdoor unit Check control wiring and connector crimps. 07 Address setting error / duplication Check indoor/outdoor unit address switches. 11 Indoor unit fan motor error Check for obstruction or a failed indoor fan motor. 31 High pressure protection activated Clean the outdoor coil and check airflow clearance. 44 Low pressure protection activated Possible refrigerant shortage — needs technician check. 13 Drain pump error Check the condensate drain for blockage. 23 Outdoor ambient sensor error Check the outdoor ambient sensor wiring. 35 Compressor overcurrent Check outdoor unit load and ventilation clearance. 41 Discharge temperature sensor error Sensor fault at compressor discharge — technician required. 47 Power factor correction (PFC) circuit error Outdoor PCB fault — needs technician diagnosis.
SS Samsung DVM (VRF) › Code Likely meaning What to check E101 Communication error between indoor and outdoor unit Check the communication cable across the whole line. E458 Outdoor unit address duplication Check outdoor module address settings. E501 High pressure protection Check outdoor coil cleanliness and ventilation clearance. E505 Compressor discharge temperature too high Possible low refrigerant charge — needs technician check. E455 Indoor unit address duplication Check indoor unit address/DIP switch settings. E462 Discharge temperature sensor error Sensor fault at compressor discharge — technician required. E468 EEPROM (memory) error Outdoor PCB fault, usually needs board service. E652 Fan motor error Check for obstruction or motor failure at the fan. E661 Power factor correction (PFC) circuit error Outdoor PCB fault — needs technician diagnosis. E699 Gas leak detection Needs a technician with gauges — not a DIY fix.
PN Panasonic ECOi (VRF) › Code Likely meaning What to check H11 Communication error between indoor and outdoor unit Check the interconnecting control wiring. F31 High pressure protection Check outdoor coil airflow and cleanliness. F41 Low pressure protection Possible refrigerant leak — needs gauge check. F97 Outdoor fan motor error Check for obstruction or motor failure at the outdoor fan. H14 Indoor temperature sensor error Check the indoor room sensor connector. F32 Low pressure sensor error Check the low pressure sensor and wiring. F49 Outdoor unit EEPROM (memory) error Outdoor PCB fault, usually needs board service. H15 Discharge temperature sensor error Sensor fault at compressor discharge — technician required. U6 Indoor/outdoor capacity mismatch Confirm indoor units match the outdoor module’s rated capacity. F91 Compressor overcurrent Check outdoor unit load and ventilation clearance.
CR Carrier (commercial & ductable) › Code Likely meaning What to check E1 Indoor room temperature sensor error Check the sensor at the return air intake. E4 Communication error between indoor and outdoor unit Inspect the control cable run. E8 Overload / high pressure protection Clean the outdoor condenser coil and check airflow clearance. PF Compressor protection fault Check outdoor unit for overheating or electrical fault. E2 Indoor coil sensor error Check the indoor coil sensor connection. E5 Outdoor sensor error Check outdoor sensor wiring and connectors. E6 Low pressure protection Possible refrigerant shortage — needs gauge check. E9 Drain pump error Check the condensate drain for blockage. PL Phase loss / phase reversal error Check the incoming power supply phasing. EE EEPROM (memory) error Outdoor PCB fault, usually needs board service.
VT Voltas Commercial › Code Likely meaning What to check F5 Communication error between indoor and outdoor unit Check the connecting control cable and terminals. F8 High pressure / overload protection Clean the outdoor condenser and check airflow clearance. F9 Outdoor fan motor fault Check for obstruction or motor failure at the outdoor fan. F1 Indoor room temperature sensor error Check the sensor at the return air intake. F2 Indoor coil temperature sensor error Check the coil sensor clip and wiring. F6 EEPROM (memory) error Outdoor PCB fault, usually needs board service. F7 Outdoor ambient temperature sensor error Check the outdoor ambient sensor connection. F10 Low pressure protection Possible refrigerant shortage — needs gauge check. F11 Compressor overcurrent Check outdoor unit load and ventilation clearance. F12 Gas leak detection Needs a technician with gauges — not a DIY fix.
BS Blue Star Ductable / Cassette › Code Likely meaning What to check E1 Room/return air sensor error Check the return-air sensor wiring. E7 Outdoor unit communication fault Check control wiring between the ductable indoor unit and outdoor unit. P1 High pressure protection Clean outdoor coil, check ductwork isn’t overly restrictive. E2 Indoor coil sensor error Check the coil sensor clip position. E3 EEPROM (memory) error Indoor/outdoor PCB fault, usually needs board service. E4 Drain pump / float switch error Check the condensate drain line for blockage. E5 Low pressure protection Possible refrigerant shortage — needs gauge check. E6 Compressor overcurrent protection Check outdoor unit load and ventilation clearance. E8 Gas leak detection Needs a technician with gauges — not a DIY fix. E9 Outdoor fan motor error Check for obstruction or motor failure at the outdoor fan.
TR Trane (North America) › Code Likely meaning What to check E1 High pressure protection Clean outdoor coil and check airflow clearance. E2 Low pressure protection Possible refrigerant shortage — needs gauge check. E3 Compressor overcurrent Check outdoor unit load and ventilation clearance. E4 Communication error between units Inspect the connecting cable and terminals. E5 Outdoor fan motor error Check for obstruction or motor failure. E6 Indoor coil sensor error Check the indoor coil sensor connection. E7 Outdoor coil sensor error Check the outdoor coil sensor connection. E8 EEPROM (memory) error PCB fault, usually needs board service. E9 Discharge temperature sensor error Sensor fault at compressor discharge — technician required. E10 Power supply voltage abnormality Check incoming voltage and phasing.
YK York (North America) › Code Likely meaning What to check P1 High pressure protection Clean outdoor coil and check airflow clearance. P2 Low pressure protection Possible refrigerant shortage — needs gauge check. P3 Compressor overload Check outdoor unit ventilation clearance. E1 Communication error between units Inspect the connecting cable and terminals. E2 Indoor sensor error Check the indoor sensor connection. E3 Outdoor sensor error Check the outdoor sensor connection. E4 EEPROM (memory) error PCB fault, usually needs board service. E5 Fan motor error Check for obstruction or motor failure. E6 Discharge temperature sensor error Sensor fault at compressor discharge — technician required. E7 Voltage or phase error Check incoming power supply phasing.
GR Gree GMV (global) › Code Likely meaning What to check E1 High pressure protection Clean outdoor coil and check airflow clearance. E2 Low pressure protection Possible refrigerant shortage — needs gauge check. E3 Compressor overcurrent Check outdoor unit load and ventilation clearance. E5 Communication error between units Inspect the connecting cable and terminals. E6 Indoor coil sensor error Check the indoor coil sensor connection. E8 Outdoor coil sensor error Check the outdoor coil sensor connection. F0 EEPROM (memory) error PCB fault, usually needs board service. F1 Discharge temperature sensor error Sensor fault at compressor discharge — technician required. F2 Fan motor error Check for obstruction or motor failure. F5 Power supply voltage abnormality Check incoming voltage and connections.
MD Midea V6 (global) › Code Likely meaning What to check E1 High pressure protection Clean outdoor coil and check airflow clearance. E2 Low pressure protection Possible refrigerant shortage — needs gauge check. E3 Compressor overload Check outdoor unit ventilation clearance. E4 Communication error between units Inspect the connecting cable and terminals. E5 Indoor sensor error Check the indoor sensor connection. E6 Outdoor sensor error Check the outdoor sensor connection. E8 EEPROM (memory) error PCB fault, usually needs board service. P0 Discharge temperature protection Sensor fault at compressor discharge — technician required. P1 Fan motor error Check for obstruction or motor failure. P2 Voltage or phase error Check incoming power supply phasing.
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