Samsung Heat Pump Error Code E406

E406 indicates a suction temperature sensor breakaway fault. The control board detected that the suction line temperature reading changed less than 2°C over a 30-minute period, which signals that the sensor is likely disconnected from its holder, has failed internally, or has a wiring problem. The suction sensor monitors refrigerant returning to the compressor, so an accurate reading is essential for safe and efficient operation.

It is not recommended to continue running the heat pump while E406 is active. The suction temperature sensor helps protect the compressor from operating under unsafe refrigerant conditions. Running the system without a reliable sensor reading risks compressor damage, which is a significantly more expensive repair than replacing a sensor or fixing a wiring issue.

Repair costs depend on what caused the fault. If the sensor simply needs to be reseated in its holder, there may be no parts cost at all, though a service call fee will still apply. Replacing a failed suction temperature sensor typically costs in the range of $100 to $300 including parts and labor. If the control board is at fault, costs can rise considerably higher, generally in the range of $400 to $800 or more depending on the model.

A homeowner with basic mechanical ability can check whether the sensor has simply come loose from its mounting clip and reseat it. However, testing sensor resistance values and inspecting refrigerant-side components properly requires tools and some technical knowledge. If the sensor itself has failed or there is a wiring fault deeper in the unit, a qualified HVAC technician should handle the repair.

A power reset may temporarily clear the fault code, but E406 will return if the underlying problem with the suction sensor or its wiring is not corrected. The control board will re-trigger the fault once it again detects 30 minutes of insufficient temperature change. A reset alone is not a repair and should not be relied on as a long-term solution.