LG Heat Pump Error Code E301

E301 indicates an OPEN or SHORT fault in the outdoor ambient temperature sensor circuit, called the OUT-TEMP sensor. The heat pump's control board monitors the resistance signal from this thermistor and triggers E301 when the signal is absent or outside acceptable limits. The system will not operate normally until the fault is resolved, as the outdoor temperature reading is essential for safe compressor and defrost control.

It is not advisable to attempt to bypass or ignore the E301 fault. The outdoor temperature sensor provides critical input for defrost cycles and compressor protection. Running the heat pump without a valid sensor signal could lead to improper defrost operation, ice buildup on the outdoor coil, or compressor damage over time. Address the fault before resuming normal operation.

A power reset may temporarily clear the E301 code if the fault was caused by a momentary issue such as a loose connection that reseated or a brief moisture event. However, if the underlying problem, such as a failed thermistor or damaged wire, has not been corrected, the error will return shortly after the unit restarts. A reset alone is not a repair and should not be used as a long-term solution.

Some basic checks are within reach for a knowledgeable DIYer. You can inspect the outdoor sensor's wiring connector for visible corrosion or disconnection, reseat the connector, and dry any visible moisture. However, accurately measuring thermistor resistance with a multimeter and safely accessing the control board inside the outdoor unit generally requires technical experience. If the sensor needs replacement, a qualified HVAC technician is recommended.

Repair costs vary depending on the root cause. If the fix is simply reseating a loose connector, you may only pay a diagnostic service fee, typically in the range of $75 to $150. If the outdoor temperature sensor needs replacement, parts and labor combined generally fall in the range of $100 to $300. A failed control board is significantly more expensive, potentially $300 to $700 or more depending on the model.