Portable Error Codes PTAC Error Codes Heat Pump Error Codes Multi Zone Air Conditioner Room/Window Air Conditioner Portable Error Codes; Error Code: E1 Cause: Electrical short on both temperature sensor and PCB Troubleshooting: Contact an electrician for repair Error Code: E2 Cause: Electrical short of temperature sensor copper tube and PCB wiring Troubleshooting: Contact an electrician for repair Error Code: E4 Cause: Indicates