LG Heat Pump Error Code E274

E274 indicates a fault in the SUMP TEMP FIXED 3 oil temperature sensor located in the outdoor unit. The control board detects that the sensor signal voltage is either above 4.95 volts, suggesting an open circuit and a reading below -30 degrees Celsius, or below 0.5 volts, suggesting a short circuit and a reading above 151 degrees Celsius. This fault is only triggered when the outdoor ambient temperature is above -10 degrees Celsius. The system shuts down to prevent compressor damage from operating without valid oil temperature data.

No. The E274 fault causes the heat pump to shut down specifically to protect the compressor from damage that could result from operating without accurate oil temperature monitoring. Attempting to bypass or ignore this fault and force the unit to run risks severe compressor damage, which is a costly repair. The system should remain off until the sensor fault is diagnosed and resolved.

A power reset may temporarily clear the E274 code, but the error will return as soon as the control board detects the out-of-range sensor voltage again. Because the fault is based on a continuous sensor signal reading, resetting the unit does not address the underlying problem. Permanent resolution requires diagnosing and correcting the sensor, wiring, or connector issue causing the voltage to fall outside the acceptable range.

Some basic checks, such as inspecting the sensor connector for loose or corroded connections, can be performed by a knowledgeable DIYer. However, properly diagnosing the fault requires measuring sensor resistance with a multimeter and interpreting the results against expected values, which requires technical knowledge. If the sensor or control board needs replacement, a qualified HVAC technician should perform the repair to ensure correct component selection and safe reassembly.

Repair costs depend on the root cause. If the issue is simply a loose or corroded connector, a service call diagnostic fee may be the primary cost, typically in the range of $75 to $150. Replacing the oil temperature sensor itself generally adds $50 to $200 in parts. If the outdoor control board has failed, parts and labor combined can range from $300 to $700 or more depending on the specific model.