LG Heat Pump Error Code E281

E281 indicates a sump temperature digital sensor open or short circuit fault on an LG heat pump. The control board has detected a signal voltage either above 4.95V (corresponding to below -30°C, indicating an open circuit) or below 0.5V (corresponding to above 151°C, indicating a short circuit). The error is only triggered when the outdoor temperature is above -10°C. The system will not operate normally until the sensor circuit is restored to a valid reading.

Operating the unit while an E281 error is active is not recommended. The sump temperature sensor is part of the outdoor unit's protection system, and bypassing or ignoring the fault could allow the unit to run without accurate sump temperature data, potentially leading to compressor damage. The system may shut itself down automatically as a protective measure.

A power cycle reset may temporarily clear the error code, but it will return if the underlying sensor circuit fault has not been corrected. Because the E281 error is tied to a measurable electrical condition (signal voltage out of the valid range), the control board will detect the same fault again on the next operating cycle. A reset is useful for confirming whether the fault is intermittent, but it is not a repair.

A knowledgeable DIYer can begin by inspecting the sensor connector at the outdoor unit for visible corrosion or loose connections, and reseating the connector may clear the fault if that is the cause. Measuring resistance across the sensor terminals requires a multimeter and basic electrical knowledge. If the sensor thermistor itself needs to be replaced or if the wiring harness is damaged, most homeowners should have a certified technician handle the repair to ensure the work is done safely and correctly.

If the fix is simply reseating a corroded connector, the cost may be limited to a service call fee, typically in the range of $75 to $150. If the sump temperature sensor thermistor needs to be replaced, parts and labor combined generally fall in the range of $150 to $350, depending on your region and the specific model. Control board replacement, if the input circuit has failed, is a more expensive repair that can range from $400 to $800 or more.