LG Heat Pump Error Code E426

E426 indicates that the outdoor unit has detected a reverse phase condition on its three-phase power supply. The control board monitors the incoming phase sequence and shuts down operation when it detects that the power phases are not in the correct rotational order. This protection feature prevents the compressor and fan motors from running in reverse, which would cause mechanical damage. The fault must be resolved before the unit will resume normal operation.

No. The E426 error causes the system to shut down automatically, and you should not attempt to bypass this protection. Running a compressor or fan motor on reversed phase rotation causes immediate mechanical damage and can lead to complete compressor failure. The system should remain off until the phase wiring is inspected and corrected by a qualified technician.

If the fix is simply correcting swapped wiring at the terminal block or disconnect, costs are typically limited to a service call fee, generally in the range of $75 to $150. If the problem involves a failing breaker leg requiring an electrician, expect $150 to $400 depending on the repair scope. In the less common case where the outdoor control board has failed and needs replacement, parts and labor can range from $400 to $900 or more depending on the model.

Diagnosing and correcting three-phase wiring involves working inside electrical panels, disconnects, and the outdoor unit's terminal block, all of which carry lethal voltages. A licensed electrician or HVAC technician should perform this work. If you are qualified to work on three-phase electrical systems, the fix often involves simply swapping two of the three power leads at the outdoor unit terminal block to correct the phase sequence, then verifying voltage balance across all three phases.

A power reset may temporarily clear the error display, but the fault will return immediately if the underlying phase wiring issue has not been corrected. Since the outdoor unit's control board checks phase sequence on startup, any incorrect wiring will be detected again as soon as power is restored. The root cause must be addressed before a reset will result in normal operation.