Samsung Air Conditioner Error Code E408

E408 indicates an open or short circuit fault on the fixed capacity compressor 1 discharge temperature sensor in the outdoor unit. The control board cannot obtain a valid temperature reading from this sensor. The error is only triggered when outdoor temperatures are above -10°C. The system will shut down or restrict operation to protect the compressor until the fault is resolved.

You should not continue operating the unit with E408 active. The discharge temperature sensor is a primary protection component for the compressor. Without accurate discharge temperature data, the system cannot detect overheating conditions, which can lead to compressor failure. Running the system in a faulted state risks expensive secondary damage.

If only the discharge temperature sensor needs replacement, parts and labor typically range from $75 to $200 depending on the unit model and local service rates. If the issue is a wiring harness, costs are similar. Replacement of the outdoor control board is more expensive and can range from $200 to $600 or more including labor. Getting a diagnostic inspection first helps narrow down the actual failed component before committing to parts costs.

A knowledgeable DIYer can check the sensor connector for corrosion and measure resistance across the sensor terminals with a multimeter to determine if the sensor has failed. However, accessing the outdoor unit control board and replacing components in a refrigerant-containing system often requires professional experience. If the sensor wiring or the board itself needs replacement, a certified HVAC technician is the safer choice.

A power reset may temporarily clear the error code, but it will return as soon as the system attempts to operate and the control board re-detects the open or short condition at the sensor. The underlying wiring or sensor fault must be physically repaired before the code will stay cleared.