LG Heat Pump Error Code E335

E335 indicates an OPEN or SHORT circuit fault on the suction temperature sensor, which is the thermistor that monitors refrigerant temperature returning to the compressor on the suction line. The control board cannot read a valid signal from this sensor and has flagged the fault to prevent potential compressor damage. The issue can be in the sensor itself, the wiring harness, or the connector.

Operating the heat pump while E335 is active is not advisable. The suction temperature sensor provides critical data that protects the compressor from running under unsafe conditions such as liquid refrigerant slugging or excessively low superheat. The control board may restrict or shut down compressor operation automatically, but continuing to attempt to run the unit without a functioning sensor risks compressor damage.

A power reset may temporarily clear the E335 error code, but if the underlying sensor or wiring fault is still present, the code will return once the control board performs its sensor checks again. A reset is useful for confirming whether the fault is intermittent, such as from a loose connector, or persistent due to a fully failed sensor. The fault should be properly diagnosed and repaired rather than relying on repeated resets.

Some basic checks are within reach of a knowledgeable DIYer, including inspecting the sensor connector for corrosion, reseating connections, and using a multimeter to measure resistance across the sensor terminals. However, replacing the suction temperature sensor involves working near refrigerant lines, and any work on the refrigerant circuit requires a certified technician. If the wiring and connector check out and the sensor itself has failed, professional repair is recommended.

If only the suction temperature sensor needs replacement, repair costs typically range from around $75 to $250 depending on labor rates and part availability. If the wiring harness is damaged, costs may be similar but will depend on the extent of the repair. In the rare case where the control board is faulty, costs can rise to $300 to $700 or more. A diagnostic service call to confirm the root cause is usually the first expense.