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Daikin Error Codes & Troubleshooting
This Daikin troubleshooting page is designed to help you understand common fault codes and take safe first-step checks before arranging a technician. Use the code list below to match displayed errors with likely system behavior.
Common Daikin issues can often be narrowed down by checking airflow cleanliness, drain path condition, and controller reset behavior. If high-priority electrical or refrigerant-related codes persist, arrange a licensed diagnostic visit to prevent escalation.
If you need help with your Daikin unit in Melbourne, our licensed team can provide same-day assessment, repair options, and maintenance guidance to keep your cooling system reliable.
Daikin Error Codes & Troubleshooting
Daikin is a leading global air conditioning manufacturer known for energy-efficient and reliable systems.
How to use this troubleshooting guide effectively
Start by matching the exact Daikin code shown on your controller and compare it with the symptom notes below. Complete only safe checks such as controller restart, filter airflow review, and visible drain condition checks. Do not open sealed electrical or refrigerant components.
If a Daikin code returns after reset or appears during every cycle, plan a full diagnostic inspection. Our Melbourne team can test sensors, communication circuits, pressures, and control logic to confirm whether repair, recalibration, or part replacement is the right next step.
Error Code: A0
External protection device activated
Troubleshooting Steps:
Check external safety devices, circuit breakers, and wiring connections. Reset if necessary.
Error Code: A1
PCB (printed circuit board) defect
Troubleshooting Steps:
Main control board malfunction. Requires professional inspection and possible replacement.
Error Code: A3
Drain pan full (overflowing)
Troubleshooting Steps:
Check drain hose for blockages. Clean drain pan and ensure proper drainage.
Error Code: A5
Heat exchanger freeze protection
Troubleshooting Steps:
System detected potential freezing conditions. Check refrigerant levels and airflow.
Error Code: A6
Fan motor defect
Troubleshooting Steps:
Indoor or outdoor fan motor malfunction. Check for obstructions and motor operation.
Error Code: A7
Swing motor fault
Troubleshooting Steps:
Swing motor malfunction. Check motor operation and remove obstructions.
Error Code: A8
Overcurrent detection
Troubleshooting Steps:
Excessive current detected. Check electrical connections and component operation.
Error Code: A9
Electronic expansion valve fault
Troubleshooting Steps:
EEV malfunction. Professional diagnosis and replacement required.
Error Code: AH
Air purification unit fault
Troubleshooting Steps:
Air purification system malfunction. Check unit operation and connections.
Error Code: C0
Sensor fault (general)
Troubleshooting Steps:
General sensor malfunction. Multiple sensors may need inspection.
Error Code: C1
Heat exchanger frost protection sensor
Troubleshooting Steps:
Frost protection sensor malfunction. Check sensor and defrost operation.
Error Code: C4
Heat exchanger (indoor unit) sensor abnormality
Troubleshooting Steps:
Temperature sensor on indoor heat exchanger is faulty. Sensor replacement required.
Error Code: C5
Heat exchanger (outdoor unit) sensor abnormality
Troubleshooting Steps:
Temperature sensor on outdoor heat exchanger is faulty. Professional diagnosis needed.
Error Code: C7
Outdoor unit heat exchanger defrosting sensor abnormality
Troubleshooting Steps:
Defrost sensor malfunction. May cause improper defrost operation in heat pump mode.
Error Code: C9
Outdoor unit suction air temperature sensor abnormality
Troubleshooting Steps:
Ambient temperature sensor fault. Check sensor wiring and connections.
Error Code: CA
Suction air temperature sensor fault
Troubleshooting Steps:
Return air temperature sensor malfunction. Check sensor operation.
Error Code: CC
Humidity sensor fault
Troubleshooting Steps:
Humidity sensor malfunction. Check sensor operation and connections.
Error Code: CJ
Remote controller temperature sensor fault
Troubleshooting Steps:
Remote controller temperature sensor error. Check remote and sensor.
Error Code: E1
Indoor unit PCB defect
Troubleshooting Steps:
Indoor unit control board failure. Requires professional replacement.
Error Code: E3
High pressure switch activation
Troubleshooting Steps:
System pressure too high. Check for refrigerant overcharge or airflow restrictions.
Error Code: E4
Low pressure switch activation
Troubleshooting Steps:
System pressure too low. Check for refrigerant leaks or undercharge.
Error Code: E5
Outdoor unit motor overcurrent
Troubleshooting Steps:
Outdoor fan motor drawing excessive current. Check for mechanical obstructions.
Error Code: E6
Compressor motor lock or overcurrent
Troubleshooting Steps:
Compressor fault. Immediate professional attention required to prevent damage.
Error Code: E7
Outdoor unit fan motor lock or overcurrent
Troubleshooting Steps:
Outdoor fan motor jammed or overloaded. Check for debris and motor operation.
Error Code: E8
Overcurrent detected
Troubleshooting Steps:
General overcurrent condition. Check electrical connections and component operation.
Error Code: E9
Electronic expansion valve fault
Troubleshooting Steps:
EEV circuit malfunction. Professional diagnosis and repair required.
Error Code: F3
Discharge pipe temperature too high
Troubleshooting Steps:
Compressor discharge temperature excessive. Check refrigerant charge and system operation.
Error Code: F6
Refrigerant pressure too high
Troubleshooting Steps:
High pressure fault. System may have overcharge or blocked condenser.
Error Code: H0
Sensor abnormality
Error Code: H1
Defrost sensor fault
Error Code: H3
High pressure switch fault
Troubleshooting Steps:
High pressure switch malfunction or activation. Check system pressures.
Error Code: H4
Low pressure switch fault
Troubleshooting Steps:
Low pressure switch malfunction. Check refrigerant levels and switch operation.
Error Code: H6
Position detection sensor fault
Troubleshooting Steps:
Sensor position error. Recalibration or replacement may be required.
Error Code: H7
Fan position sensor fault
Troubleshooting Steps:
Fan position detection error. Check fan motor and sensor operation.
Error Code: H8
CT (current transformer) abnormality
Troubleshooting Steps:
Current sensing circuit fault. Professional electrical diagnosis required.
Error Code: H9
Outdoor air temperature sensor abnormality
Troubleshooting Steps:
Outdoor ambient sensor fault. Check sensor and wiring connections.
Error Code: J3
Discharge pipe temperature sensor abnormality
Error Code: J6
Heat exchanger temperature sensor abnormality
Troubleshooting Steps:
Heat exchanger temperature sensor malfunction. Affects system efficiency.
Error Code: J7
Suction pipe temperature sensor fault
Troubleshooting Steps:
Suction line temperature sensor malfunction. Check sensor operation.
Error Code: J8
Liquid pipe temperature sensor fault
Troubleshooting Steps:
Liquid line temperature sensor malfunction. Professional diagnosis needed.
Error Code: L3
Electrical box temperature rise
Troubleshooting Steps:
Control box overheating. Check ventilation and electrical connections.
Error Code: L4
Inverter radiator temperature rise
Troubleshooting Steps:
Inverter heat sink overheating. Check cooling and component operation.
Error Code: L5
Compressor motor temperature rise
Troubleshooting Steps:
Compressor overheating. Check refrigerant levels and system operation.
Error Code: L8
Inverter circuit overheating
Troubleshooting Steps:
Inverter circuit overheating. Check cooling system and ventilation.
Error Code: LC
Refrigerant line temperature sensor fault
Troubleshooting Steps:
Refrigerant line sensor malfunction. Check sensor and connections.
Error Code: P1
Phase detection abnormality
Error Code: P3
Electrical box temperature sensor fault
Troubleshooting Steps:
Control box temperature sensor malfunction. Check sensor operation.
Error Code: P4
Inverter radiator temperature sensor abnormality
Error Code: P7
Outdoor unit total current sensor fault
Troubleshooting Steps:
Current sensor malfunction. Check electrical connections and sensor.
Error Code: PJ
Compressor overload or overcurrent
Troubleshooting Steps:
Compressor protection activated. System requires immediate professional attention.
Error Code: U0
Refrigerant shortage
Troubleshooting Steps:
Low refrigerant detected. Check for leaks and recharge system if needed.
Error Code: U1
Reverse phase or phase loss
Troubleshooting Steps:
Power supply phase error. Check electrical connections and phase sequence.
Error Code: U2
Voltage drop or power supply abnormality
Troubleshooting Steps:
Insufficient power supply voltage. Check electrical connections and supply voltage.
Error Code: U3
Control signal error
Error Code: U4
Communication abnormality
Troubleshooting Steps:
Communication error between indoor and outdoor units. Check connecting cables.
Error Code: U5
Remote control reception error
Error Code: U7
Remote controller communication error
Troubleshooting Steps:
Remote controller communication fault. Check controller and connections.
Error Code: U8
Main remote controller and sub controller conflict
Troubleshooting Steps:
Controller conflict detected. Check controller settings and connections.
Error Code: UA
Central control and local control conflict
Error Code: UF
Gas shortage
Troubleshooting Steps:
Refrigerant shortage detected. Professional leak detection and recharge required.
Error Code: UH
System setting error
Troubleshooting Steps:
System configuration error. Check system settings and parameters.
Still Having Issues with Your Daikin System?
Our certified technicians are experts in Daikin air conditioning systems. We provide professional diagnosis, repair, and maintenance services across Melbourne.
Available 24/7 for emergencies
Prevent future faults with routine maintenance
On Daikin systems, recurring codes are commonly linked to airflow restriction, drain blockages, sensor drift, or overdue seasonal servicing. Preventive maintenance helps stabilise efficiency, reduce nuisance shutdowns, and keep warranty conditions on track.
We recommend a professional service before summer to test performance, clean critical components, and confirm your Daikin system is operating safely and reliably.