I just installed a Carrier Mini-Split and am getting an E2 error code. I have already replaced both boards in the outdoor unit IMP and Main PC with no luck. Any suggestions?

PC4 is an error code that indicates a communication error between the outdoor unit and the indoor unit of the system. This could be due to a faulty wiring connection between the two units, or due to a defective control board. You should check all wiring connections and, if necessary, replace the control board to resolve the error.

On a Haier Split system a E7 error is a failure of the outdoor inverter PCB and the outdoor power supply PCB. Both will need replacing. Looking around $600 for those parts. Plus fitting. The indoor PCB is very unlikely to be needed.

It looks like a generic code for 'Pressure Protection'.

https://www.shareddocs.com/hvac/docs/1009/Public/0E/MS-DLFSHB-01.pdf

https://www.google.com/search?q=error+code+pc+0

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Possible Causes of P6 Mini Split Error Code
Wiring Problem
Faulty IPM Board
Faulty Outdoor Fan Assembly
Compressor Malfunction
Faulty Outdoor PCB Board
A P6 may be caused by wiring mistake, faulty IPM board, faulty outdoor fan, assembly compressor malfunction, and faulty outdoor PCB.
How To Fix or Clear an P6 Mini Split Error Code
Power off the unit and turn off the breaker or disconnect.
Wait 2-3 minutes and power the unit back on.

Full list of Gree Air Conditioner Mini Split Units Fault Codes. When error codes appear on the Gree air conditioner indoor display, this tells the user there is an issue with the Gree AC unit. The error code displayed will inform you of the issue or problem that is occurring with the air conditioner. Knowing what the error code means and its definition will help you to understand and troubleshoot the exact Gree air conditioner part that needs to be fixed, cleaned, repaired, or replaced. You can then clean, fix, or replace the Gree part yourself and save money. See below for all error codes that can occur on Gree Mini Split AC's.
Gree Mini Split Air Conditioner Error Codes - How To Fix
Gree Viero AC Mini Split PDF Owners and Troubleshooting Manual
GREE DUCTLESS AIR CONDITIONING & HEATING SYSTEM INSTALLATION MANUAL

Gree Mini Split Air Conditioner Part Names and Locations
INDOOR AND OUTDOOR UNIT
The Gree Air Conditioning Vireo System has onboard error code diagnostics. The outdoor unit will provide status indicators and the indoor wall unit and remote control will display error codes. The following is a summary of the codes with explanations...
GREE AC DIAGNOSTIC ERROR CODES
Gree Vireo Mini Split Air Conditioner Error Code F0
Refrigerant Leakage Protection
1) Refrigerant leak(s).
2) Indoor coil temperature sensor not calibrated.
3) Refrigerant flow is restricted (ex. valve, exv, debris)
Outdoor Unit Red Light Indicator - 9 flashes and 1 sec Off
Gree Vireo Mini Split Air Conditioner Error Code E1
System High Pressure
1) Over charged with refrigerant.
2) Blocked or dirty outdoor coil.
3) Extreme outdoor ambient conditions
Gree Vireo Mini Split Air Conditioner Error Code E2
Indoor Anti-Freeze Protection
1) Low return airflow.
2) Indoor fan speed is too low.
3) Indoor coil is blocked or dirty.
Outdoor Unit Yellow Light Indicator - 3 flashes and 1 sec Off

Gree Vireo Mini Split Air Conditioner Error Code E4
Compressor High Discharge Temperature Protection
Please refer to the malfunction analysis (discharge temperature, overload) in service manual.
Outdoor Unit Yellow Light Indicator - 7 flashes and 1 sec Off
Gree Vireo Mini Split Air Conditioner Error Code E5
Overcurrent Protection
1) Supply voltage is unstable.
2) Supply voltage is too low and system load is too high.
3) Indoor coil is blocked or dirty.
Outdoor Unit Yellow Light Indicator - 5 flashes and 1 sec Off
Gree Vireo Mini Split Air Conditioner Error Code E6
Communication Malfunction
1) Communication cable is wired incorrectly between indoor and outdoor units.
2) Indoor or Outdoor control board malfunction.
Outdoor Unit Yellow Light Indicator - Continuous On
Gree Vireo Mini Split Air Conditioner Error Code E8
High Temperature Resistant Protection
1) Incorrect refrigerant charge level.
2) Refrigerant metering device malfunction.
3) Compressor malfunction.
Outdoor Unit Yellow Light Indicator - 6 flashes and 1 sec Off
Gree Vireo Mini Split Air Conditioner Error Code EE
EEPROM Memory Malfunction
Control board malfunction.
Outdoor Unit Yellow Light Indicator - 11 flashes and 1 sec Off
Gree Vireo Mini Split Air Conditioner Error Code C5
System Configuration Malfunction
1) No jumper cap inserted on the control board.
2) Incorrect or damaged jumper cap on control board.
3) Indoor and outdoor units are not compatible.
Gree Vireo Mini Split Air Conditioner Error Code Fo
Pump Down or Gathering Refrigerant Status
Optional Service Mode
Outdoor Unit Yellow Light Indicator - 17 flashes and 1 sec Off

NOTE: All of the Gree Air Conditioner Model Numbers below are applicable for the error codes on this page...
Gree AC Vireo Models: VIR09HP115V1A, VIR12HP115V1A, VIR09HP230V1A, VIR12HP230V1A, VIR18HP230V1A, VIR24HP230V1A, VIR30HP230V1A, and VIR36HP230V1A.
Gree Mini Split Air Conditioner Error Code Charts
Gree Mini Split AC Remote Control Button Names
Gree Mini Split AC Remote Control Icons Display Screen

Gree Mini Split Air Conditioner Air Filter Cleaning Procedure
Gree Viero AC Mini Split PDF Owners and Troubleshooting Manual
GREE DUCTLESS AIR CONDITIONING & HEATING SYSTEM INSTALLATION MANUAL
Need help with error codes on your Gree AC? Please leave a question below and we will be happy to help.

Get the model number of your mini split unit (on tag on indoor unit and outdoor unit) Google hitachi error codes. You should be able to pull up a code list for that unit. I believe it may be a communication problem between the indoor and outdoor unit. Possible bad connection of wire going from outdoor to indoor unit

If your mini split was installed to meet most building codes, an inside disconnect switch should have been installed. This switch breaks the power and signal from the outdoor unit to the indoor unit. It is not the same as the outside disconnect to the compressor (outdoor unit). If it was turned off, the inside unit would be dead. Look for a disconnect switch inside your room. By code is should be within 15 feet of the inside unit.

Check the outdoor unit to ensure power is available to it, and the contactor is closing on a call for cool 24-28 volt is present at the contactor coil to activate it.

F1 error code is a communication failure between the outdoor and indoor units. Check all inter-connecting wires. They should be minimum 14g stranded wire. Make sure all electrical connections are tight. These units are manufactured by CHIGO, you may try to contact them.