Hitachi AC Error Codes – Causes and Solutions

Hitachi, Ltd. is a Japanese multinational corporation – that is the parent company of Hitachi Group. With headquarters in Chiyoda, Tokyo the company has found itself in the middle of a technology hub. With a stake in IT and AI workings, the company is all set to change the infrastructure of the world.

Founded in 1919, by Namihei Odaira the company then produced induction motors used in copper mining. Since then the company has come a long way and now offers a wide range of commercial and residential appliances that are used all over the world. With their air conditioners taking the lead, back in the day as window air conditions, and now as sleek and simple ACs. While being at top of their game, it is no secret that some users are facing ac error codes that are unable to handle.

While there are times when a simple issue might seem like a great deal, one of these is an ac error code, especially during the summer season. The best way to deal with the situation is to note down the error code and match it using the list below. Once you have the error code you can easily work your way to the fix. To help you out we have listed down some of the most common error codes for Hitachi ACs.

Codes List

Multi-split System, Heat Pump AC

Error CodeProtection Control
P01Pressure ratio protection control
P02High pressure increase protection
P03Inverter current protection
P04Inverter fin temperature increase protection
P05Discharge gas temperature increase protection at the upper part of the compressor
P06Low pressure decrease protection
P09High pressure decrease protection
P0ADemand current protection control
P0dLow pressure increase protection
P11Pressure ratio decrease retry
P12Low pressure increase retry
P13High pressure increase retry
P14Constant speed compressor overcurrent retry
P15Discharge gas temperature increase retry / Low pressure decrease retry
P16Discharge gas super-heat decrease retry
P17Inverter anomaly retry
P18Abnormal Inverter voltage retry / Inverter failure retry
P26High pressure decrease retry

Self-Diagnostic Malfunction Codes

Hitachi Self-Diagnostic Malfunction Error Codes
Hitachi Self-Diagnostic Malfunction Error Codes

If the unit malfunctions then an error code will display on the controller as below. Error codes and Drive Error Codes can also be interrogated using the Running Parameter function on the controller. They are also displayed on the outdoor PCB.

Alarm CodesCause
01Tripping of Protection Device-Failure of Fan Motor, Drain Discharge, PCB, Relay.
02Tripping of Protection Device-Activation of PSH.
03Abnormality between Indoor (or outdoor) and Outdoor (or Indoor)-Incorrect Wiring. Failure of PCB. Tripping of Fuse. Power Supply OFF.
04Abnormality between Inverter and Control PCB-Failure in Transmission between PCBs.
05Abnormality of Power Source Wiring-Reverse Phase Incorrect Wiring.
06Voltage Drop by Excessively Low or High Voltage to Outdoor Unit-Voltage Drop of Power Supply, Incorrect Wiring or Insufficient Capacity of Power Supply Wiring.
07Decrease in Discharge Gas Superheat-Excessive Refrigerant Charge, Expansion Valve Open Lock.
08Increase in Discharge Gas Temperature-Insufficient Refrigerant. Ref. Leakage, Clogging or Expansion Valve Close Lock.
09Tripping of Protection Device-Failure of Fan Motor.
11Inlet Air Thermistor-Failure of Thermistor, Sensor, Connection.
12Outlet Air Thermistor-Failure of Thermistor, Sensor, Connection.
13Freeze Protection Thermistor-Failure of Thermistor, Sensor, Connection.
14Gas Piping Thermistor-Failure of Thermistor, Sensor, Connection.
19Failure of Fan Motor-Failure of Fan Motor.
21High Pressure Sensor-Failure of Thermistor, Sensor, Connection.
22Outdoor Air Thermistor-Failure of Thermistor, Sensor, Connection.
23Discharge Gas Thermistor on Comp-Failure of Thermistor, Sensor, Connection.
24Evaporating Thermistor-Failure of Thermistor, Sensor, Connection.
29Low Pressure Sensor-Failure of Thermistor, Sensor, Connection.
30Incorrect Wiring Connection-Incorrect Wiring Connection between Outdoor Unit, CH Unit and Indoor Unit.
31Incorrect Setting of Outdoor and Indoor Unit-Incorrect Setting of Capacity Code.
32Abnormal Transmission of Other Indoor Unit-Failure of Power Supply, PCB in Other Indoor Unit. Failure of Other Indoor Unit of the Same Refrigerant Cycle.
35Incorrect Setting in Indoor/Outdoor Unit No-Existence of the same Indoor Unit No. in the same refrigerant cycle.
38Abnormality of Protective Circuit in Outdoor Unit-Failure of Indoor Unit PCB. Incorrect Wiring Connection to PCB in Outdoor Unit.
39Abnormality of Running Current at Constant Compressor-Overcurrent, Melted Fuse of Failure of Current Sensor.
43Pressure Ratio Decrease Protection Activating-Failure of Compressor, Inverter.
44Low Pressure Increase Protection Activating-Overload to Indoor in Cooling, High Temperature of Outdoor Air in Heating Expansion Valve Open Lock.
45High Pressure Increase Protection Activating-Overload Operation. Excessive Refrigerant Clogging of Heat Exchanger.
46High Pressure Decrease Protection Activating-Insufficient Refrigerant.
47Low Pressure Decrease Protection Activating-Insufficient Refrigerant. Expansion Valve Close Lock. Refrigerant Leakage.
51Abnormality of Current Sensor for Inverter-Failure of Sensor on Inverter PCB.
52Overcurrent Protection Activating-Overload, Overcurrent, Locked to Compressor.
53IPM Protection Activating-Automatic Stoppage of IPM.
54Increase in Inverter Fin Temperature-Abnormal Inverter Fin Thermistor, Abnormal Outdoor Fan.
56Abnormality of Detection for Fan Motor Position-Abnormal Detection Circuit of Transmission.
57Fan Controller Protection Activating-Abnormal Fan Speed.
58Abnormality of Fan Controller-Overcurrent, Abnormal Fan Controller Fin.
59AC Chopper Circuit Protection-Failure of FET, Power Supply, CT for Fan Motor.
76Freeze protection stop by indoor liquid refrigerant temperature thermistor.
78RF Communication failure. No communication for 1 hour with one or two RF receivers which are bound to the RF-Bridge.
EECompressor Protection-3 Time Occurrence of Alarm Giving Damage to Compressor within 6 hours.
ddIncorrect Wiring between Indoor Units-Incorrect Wiring between Indoor Units and Remote Control Switch.
Hitachi Remote Control Display Meaning
Hitachi Remote Control Display Meaning

Remote Controller Alarm Codes

Regarding the retry control, the lastest retry code will be indicated unless the protection control related with the frequency control is indicated.

Hitachi AC Error Codes and Troubleshooting
01Safety Device of the Indoor Unit is tripped (internal Thermostat, *Float Switch)
021. Safety Device of the Outdoor Unit is tripped (High pressure switch, Internal Thermostat for Outdoor Fan Motor and Overcurrent Relay) 2. Safety Device of the Outdoor Unit is tripped (Overcurrent Relay, Compressor Chamber Thermostat, High Pressure Switch and Internal Thermostat for Outdoor and Indoor Fan Motor)
03Transmission Abnormality between Indoor Unit and Outdoor Unit
05Picking up phase Abnormality
08Abnormality High Temperature on the Top of Compressor
11Thermistor Abnormality for inlet Air Temperature
12Thermistor Abnormality for outlet Air Temperature
13Thermistor Abnormality for Freezing Temperature
20Thermistor Abnormality for Compressor Top Temperature
22Thermistor Abnormality for Outdoor Air Temperature
24Thermistor Abnormality for Outdoor Evaporating Temperature (defrosting)
25Thermistor Abnormality for Condensing Temperature
32Transmision Abnormality between Master and Slave
38Abnormality in the Picking up Circuit protection
41Excessive Overload during Cooling Operation
42Excessive Overload during Heating Operation
Hitachi Split System Heat Pump AC Error Codes
Hitachi Split System Heat Pump AC Error Codes

Inverter AC Codes List

Error codeMalfunction
E0Water pump malfunction
E1High pressure protection of compressor
E2Indoor anti-frozen protection
E3Low pressure protection of compressor
E4Air discharge high-temperature protection of compressor
E5Overload protection of compressor or Inverter error
E6Communication malfunction
E8Indoor fan protection
E9Water flow protection
F0Malfunction of indoor environment sensor at air return vent
F1Evaporator sensor malfunction
F2Condenser sensor malfunction
F3Outdoor environment sensor malfunction
F4Malfunction of air discharge sensor
F5Malfunction of environment sensor on displayer
EHAuxiliary electric heater malfunction
H1Indoor unit fault
H2Indoor ambient temperature
H3Indoor coil temperature
H4Indoor setting temperature
FECommunication between main control board and wiring remote controller fault.
ERCommunication between main control board and display board fault.
Hitachi AC Remote Control Button Meaning
Hitachi AC Remote Control Button Meaning

RAC Fault Codes – (Indoor Units Flashing)

Timer LightCause
1 FlashInsufficient heating or cooling. Likely low on refrigerant.
2 FlashesOutdoor unit is in forced operation. Not a fault.
3 FlashesIndoor/Ourdoor communication error. Check interconnecting cable.
4 FlashesOutdoor unit error. Check outdoor unit.
5 FlashesIndoor fan motor rotation error. Check indoor fan motor.
6 FlashesDrain high water level alarm. Check drains and pump.
7 FlashesDrain pump in force operation. Not a fault.
8 FlashesLouver defective. Check louvers and wiring.
9 FlashesIndoor thermistor fault. Check air and pipe thermistor.
10 FlashesFan rotation error. Check indoor fan motor.
11 FlashesHigh voltage genorator/Ionize fault. Check high voltage gen/Ionizer.
12 FlashesIndoor/Outdoor communication error. Check interconnecting cable.
13 FlashesEEPROM error on PCB. Check PCB.


Hissing or fizzy soundsRefrigerant flow noise in the pipe or valve sound generated when flow rate is adjusted.
Squeaking noiseNoise generated when the unit expands or contracts due to temperature changes.
Rustling noiseNoise generated with the indoor unit fan’s rpm changing such as operation start times.
Clicking noiseNoise of the motorized valve when the unit is switched on.
Perking noiseNoise of the ventilation fan sucking in air present in the drain hose and blowing out dehumidifying water that had accumulated in the condensed water collector. For details, consult your sales agent.
Changing operation noiseOperation noise changes due to power variations according to room temperature changes.
Mist emissionMist is generated as the air within the room is suddenly cooled by conditioned air.
Steam emitted from the outdoor unitWater generated during defrosting operation evaporates and steam is emitted.
OdorsCaused as the smells and particles of smoke, food, cosmetics, etc. present in room air become attached the unit and blown off into the room again.
The outdoor unit continues to operate even if operation is stopped.Defrosting is underway (as the heating operation is stopped, the microcomputer checks frost accumulated in the indoor unit and instructs the unit to perform automatic defrosting if necessary).
The OPERATION lamp is blinking.Shows preheating or defrosting operation is underway. As the protective circuit or preheat sensor operates when unit operation is stopped during preheating and then restarted, or when operation mode is switched from cooling to heating, the lamp continues to blink.
Does not reach the temperature setting.Actual room temperature may deviate slightly from the remote controller’s temperature setting depending on the number of people in the room, indoor or outdoor conditions.

Wiring Diagrams

Typical Indoor Unit Electric Wiring Diagram
Typical Indoor Unit Electric Wiring Diagram
Typical Outdoor Unit Electric Wiring Diagram
Typical Outdoor Unit Electric Wiring Diagram

Manuals Pdf

AC Manual PDF

AC Manual PDF-2

Split System Heat Pump AC Manual

*If you can't find the code you're looking for on our site, please let us know, and we'll update our database as soon as possible.

60 thoughts on “Hitachi AC Error Codes – Causes and Solutions”

  1. P4 error code on Hitachi RAS/RAC 19HV split type dc inverter aircon ….outdoor unit fan running for sometime but not the compressor then eventually unit stop with P4 error on the indoor unit display…..what and where could be the problem….thanks


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