Error Code	Symptom	Fault Type	Guide
E0	Indoor unit displays E0 and will not respond to remote commands or buttons	EEPROM Parameter Error / Indoor PCB Configuration Fault	View Details
E1	Indoor unit shows E1 and stops cooling or heating shortly after startup	High-Pressure Protection / Refrigerant System Overpressure	View Details
E2	Indoor unit displays E2 and stops cooling; may run fan only	Indoor Evaporator Coil Freeze Protection / Low Temperature Protection	View Details
E3	Indoor unit shows E3 and stops; outdoor unit may shut down shortly after starting	Low-Pressure Protection / Refrigerant Undercharge or Flow Restriction	View Details
E4	Indoor unit displays E4 and shuts down during heating mode	Defrost Protection / Outdoor Coil Overheat or Frost Fault	View Details
E5	Indoor unit shows E5 and will not start compressor; fan may still run	Overcurrent Protection / Compressor Overload	View Details
E6	Indoor unit displays E6 and does not cool or heat; outdoor unit may not start	Communication Failure Between Indoor and Outdoor Units	View Details
E7	Indoor unit shows E7 and system will not operate in one or more modes	Mode Conflict / Indoor-Outdoor Mode Mismatch	View Details
E8	Indoor unit displays E8 and may shut down unexpectedly, especially in high load conditions	Overload Protection / Indoor Fan or System Overload	View Details
E9	Indoor unit shows E9 and may leak water or stop cooling	Water Overflow Protection / Drainage Fault	View Details
F0	Indoor unit displays F0 and system does not cool properly	Refrigerant Undercharge / Low Refrigerant Protection	View Details
F1	Indoor unit shows F1 and may run fan only with no cooling	Indoor Ambient Temperature Sensor (Room Sensor) Fault	View Details
F2	Indoor unit displays F2 and may stop cooling or heating	Indoor Evaporator Coil Temperature Sensor Fault	View Details
F3	Indoor unit shows F3, often during heating mode	Outdoor Ambient Temperature Sensor Fault	View Details
F4	Indoor unit displays F4 and system may not heat properly	Outdoor Condenser/Coil Temperature Sensor Fault	View Details
F5	Indoor unit shows F5 and may stop during heating defrost cycles	Outdoor Discharge Pipe Temperature Sensor Fault	View Details
F6	Indoor unit displays F6 and cooling capacity is reduced	Indoor Fan Speed Out of Control / Feedback Error	View Details
F7	Indoor unit shows F7 and outdoor unit may not respond	Outdoor Fan Speed Abnormal / Feedback Error	View Details
F8	Indoor unit displays F8 and system may shut down under heavy load	Inverter Module Overheat / IPM Overtemperature Protection	View Details
F9	Indoor unit shows F9 and may not maintain set temperature accurately	Indoor Auxiliary Temperature Sensor Fault (e.g., Pipe or Mid-Coil Sensor)	View Details
H0	Indoor unit displays H0 and system may not start or may run in limited mode	Indoor EEPROM or Configuration Mismatch	View Details
H1	Indoor unit shows H1 and no warm air is produced at the start of heating	Defrost or Preheat Mode Indication (Not Always a Fault)	View Details
H2	Indoor unit displays H2 and heating performance is poor or intermittent	Compressor Overheat Protection in Heating	View Details
H3	Indoor unit shows H3 and system shuts down under heavy cooling load	Compressor Overload / Overcurrent Protection	View Details
H4	Indoor unit displays H4 and may not respond to mode changes	Indoor-Outdoor Mismatch or Capacity Code Error	View Details
H5	Indoor unit shows H5 and system may not start or may shut down quickly	IPM (Inverter Power Module) Protection / Drive Fault	View Details
H6	Indoor unit displays H6 and outdoor fan does not run	Outdoor Fan Motor Lock or Feedback Fault	View Details
H7	Indoor unit shows H7 and compressor does not start	Compressor Position or Phase Error (Inverter Models)	View Details
H8	Indoor unit displays H8 and system may run at reduced capacity	Indoor Fan Motor Overload or Stall	View Details
H9	Indoor unit shows H9 and room temperature control is erratic	Remote Controller or I-Feel Sensor Fault (on models with built-in sensor in remote)	View Details
–	Breaker trips whenever the air conditioner starts or shortly after	Overcurrent / Electrical Short	View Details
–	Indoor unit and outdoor unit both run but cooling is weak; supply air only slightly cooler than room	Reduced Cooling Capacity / Refrigerant or Airflow Problem	View Details
–	Indoor unit blows warm air in COOL mode or cool air in HEAT mode	Reversing Valve or Mode Control Failure	View Details
–	Indoor unit displays lights but airflow is very weak even on high fan setting	Restricted Indoor Airflow	View Details
–	Indoor unit does not power on at all; no lights or display	No Power to Indoor Unit	View Details
–	Indoor unit emits clicking or popping noises during operation or when starting/stopping	Thermal Expansion and Plastic Casing Noise	View Details
–	Indoor unit fan runs but compressor and outdoor fan start and stop repeatedly within seconds	Unstable Inverter Operation / DC Bus or Control Fault	View Details
–	Indoor unit powers on but will not respond to remote control commands	IR Receiver or Remote Control Failure	View Details
–	Indoor unit produces a musty or moldy odor when starting	Biological Growth on Evaporator Coil and Drain Pan	View Details
–	Indoor unit runs but no cooling; air is room temperature and outdoor unit does not start	Outdoor Unit Not Energizing / Control or Power Supply Fault	View Details
–	Indoor unit vibrates excessively or makes knocking sounds, especially at high fan speed	Indoor Vibration / Fan Imbalance	View Details
–	Outdoor unit makes loud rattling, buzzing, or grinding noises during operation	Outdoor Mechanical Noise / Fan or Compressor Issue	View Details
–	System frequently short cycles (turns on and off every few minutes) without reaching set temperature	Short Cycling / Control or Capacity Issue	View Details
–	Water dripping from the front of the indoor unit or down the wall	Indoor Unit Water Leak / Condensate Drainage Problem	View Details

Pioneer Air Conditioners Error Codes

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