Samsung Air Conditioner Error Code E418

Error code E418 on a Samsung air conditioner indicates a sump sub 3 sensor breakaway error, meaning the temperature sensor mounted on the number 3 compressor sump has become physically separated from its mounting position. The sump sensor monitors the temperature at the base of the compressor to protect it from overheating and to ensure proper refrigerant management. When this sensor loses contact with the compressor sump surface, the control board receives inaccurate or absent temperature readings, triggering the E418 fault and halting normal operation to prevent potential compressor damage.

This type of error is classified as a physical disconnection fault rather than an electrical failure. The sensor itself is typically clipped, clamped, or otherwise fixed directly against the compressor sump housing. Vibration from normal operation, improper installation, or loosening of the retaining hardware over time can cause the sensor to pull away from the mounting point. Once separated, the sensor reads ambient air temperature instead of the actual sump temperature, which throws off compressor protection logic.

The primary diagnostic step is a visual inspection of the number 3 compressor sump sensor to confirm it has come free from its secured position. If the sensor body and wiring are undamaged, reassembling the sensor back onto the sump and securing it properly will typically resolve the fault. If the sensor clip, bracket, or adhesive pad is damaged, replacement of the retaining hardware or the sensor assembly itself may be required before the unit will clear the error and resume normal operation.