LG Heat Pump Error Code E164

E164 means the system detected no change in the evaporator inlet temperature during its piping check routine. This test verifies that refrigerant is flowing properly through the circuit and that the Electronic Expansion Valve is responding to commands. A static sensor reading during this test tells the control board that something is preventing normal refrigerant flow or thermal response. The most common causes are EEV coil seating issues, wiring faults, or an indoor unit address mismatch.

Continuing to operate the system with E164 active is not advisable. The error indicates the refrigerant circuit is not functioning as expected, which can lead to inadequate heating or cooling and potential stress on the compressor if it runs without proper refrigerant flow. The system should be inspected and the fault resolved before returning to normal operation.

Repair costs vary depending on the root cause. If the fix is simply reseating an EEV coil or correcting an address setting, labor costs alone may be in the range of $75 to $150. If the Electronic Expansion Valve needs to be replaced, total costs including parts and labor can range from $300 to $700 or more depending on the system model and local rates. A technician diagnosis is needed to give an accurate estimate.

Some causes of E164 can be addressed by a knowledgeable DIYer, such as verifying the indoor unit address setting or reseating a loose EEV coil connector. However, diagnosing EEV operation, checking refrigerant flow, and replacing components typically require refrigerant handling certification and specialized tools. It is recommended to have a qualified HVAC technician perform the full diagnosis if basic checks do not resolve the fault.

A power reset may temporarily clear the fault display, but E164 will return if the underlying problem is not corrected. The error is triggered by the piping check routine, which will run again after a reset and detect the same issue if the EEV, wiring, or address configuration has not been corrected. A reset should only be used as part of a diagnostic process, not as a standalone fix.