LG Air Conditioner Error Code E151

E151 indicates that the indoor unit's Electronic Expansion Valve (EEV) has been detected as stuck open on a second consecutive check, meaning the valve will not close properly. The system logs this as a second-detection fault and stops normal operation to protect the refrigerant circuit and compressor. The root cause is typically a wiring fault, a failed EEV coil, or a mechanically failed valve body.

No, it is not advisable to continue running the unit when E151 is active. A stuck-open EEV disrupts proper refrigerant metering, which can cause liquid refrigerant to reach the compressor and cause serious damage. The system typically shuts itself down for this reason, and it should remain off until the fault is resolved.

A power reset may temporarily clear the error display, but E151 is a second-detection fault, meaning the system has already confirmed the problem on two separate checks. If the underlying issue with the EEV coil, wiring, or valve body is not corrected, the error will return quickly after the unit attempts to operate again. A reset alone is not a repair.

A homeowner can start by checking that the EEV wiring harness connectors are fully seated and free of visible corrosion. However, measuring coil terminal resistance, diagnosing the PCB, or replacing the EEV requires technical knowledge and specialized tools. Most repairs beyond the initial wiring check should be handled by a certified HVAC technician.

Repair costs vary depending on the root cause. If only a wiring connection needs to be reseated, the cost may be limited to a service call fee, generally in the range of $75 to $150. Replacing an EEV coil typically costs between $50 and $150 for the part plus labor, while replacing the full valve body or the main PCB can bring total costs to $200 to $600 or more depending on the model and labor rates.