LG Heat Pump Error Code P431

P431 indicates that heating mode operation has been prohibited because the outdoor temperature sensor is reading above 30°C (86°F). This is a built-in operational restriction, not a component failure. The unit is preventing heating mode from running under conditions that exceed its designed temperature boundary. If outdoor temps are not actually that high, the outdoor temperature sensor should be inspected.

No, P431 is not a safety hazard. It is a protective operational restriction that prevents the heat pump from running heating mode under outdoor temperature conditions outside its design range. The system is functioning as intended when this code appears.

If the restriction is triggered by actual high outdoor temperatures, there is no repair cost involved. If a faulty outdoor ambient temperature sensor is the cause, sensor replacement parts typically range from around $20 to $80 depending on the model, with labor costs for a technician adding $75 to $200 or more depending on your location and service provider.

Start by comparing the temperature displayed by the system against an actual thermometer reading taken near the outdoor unit in a shaded spot. If outdoor temperatures truly exceed 30°C, the code will clear on its own once temps drop. If the sensor reading is inaccurate, check the sensor placement for localized heat sources, inspect the sensor wiring for damage, and test the sensor resistance to determine whether replacement is needed.

A reset may temporarily clear the code, but it will return if the outdoor temperature sensor continues to read above 30°C, whether due to actual high temperatures or a faulty sensor. Resetting without addressing the underlying cause is not a lasting solution. The root cause, either actual ambient temperature or a sensor issue, must be resolved first.