LG Heat Pump Error Code E311

E311 indicates a PWM discharge temperature sensor error caused by an OPEN or SHORT circuit in the sensor circuit. The system detects this fault when the sensor signal voltage exceeds 4.95V (open circuit, corresponding to a reading below -30°C) or drops below 0.5V (short circuit, corresponding to a reading above 151°C). This error only activates when the outdoor ambient temperature is above -10°C. The unit will shut down to protect the compressor until the fault is resolved.

No, you should not attempt to bypass or ignore this error. The discharge temperature sensor protects the compressor by detecting overheating conditions in the refrigerant circuit. Without reliable temperature data, the control system cannot prevent compressor damage from excessively high discharge temperatures. The unit is designed to shut down when this error is active for this reason.

Repair costs vary depending on the root cause. If only the connector needs cleaning or reseating, costs may be limited to a service call fee, typically in the range of $75 to $150. Replacing the discharge temperature sensor itself is generally a lower-cost parts repair, with sensors often ranging from $20 to $80 in parts plus labor. If the outdoor control board is at fault, total repair costs including parts and labor could range from $300 to $700 or more depending on the model and local rates.

A knowledgeable DIYer can perform basic checks such as inspecting the sensor connector at the outdoor unit and visually examining the wiring harness for obvious damage. However, accurately measuring sensor resistance and diagnosing whether the fault lies in the thermistor, wiring, or control board requires a multimeter and familiarity with the outdoor unit layout. Refrigerant system components are nearby, so if the repair goes beyond connector checks, a licensed technician is recommended.

A power reset may temporarily clear the error display, but the code will return if the underlying sensor fault is still present. The error is tied to a real electrical condition, either an open or short circuit in the sensor, and the system will re-detect it once operation resumes and outdoor temperatures are above -10°C. A permanent fix requires diagnosing and correcting the wiring or replacing the faulty sensor.