Samsung Air Conditioner Error Code E123

E123 indicates an open or short circuit fault on the indoor heat exchanger evaporator outlet temperature sensor. The control board cannot read a valid signal from this sensor due to a disconnected connector, a broken wire, or a failed sensor. The unit will stop normal operation until the fault is resolved.

No. The E123 fault causes the unit to disable normal operation because without accurate evaporator outlet temperature data, the system cannot properly manage the cooling cycle. Running the unit with a faulty or missing sensor signal risks evaporator freeze-up or improper refrigerant management, which can cause additional component damage.

If the fix is simply reseating a loose connector, there may be no parts cost beyond a service call fee. If the EVAP OUT sensor needs replacement, parts and labor typically range from $80 to $200 depending on the unit model and local labor rates. A broken wire repair falls in a similar range depending on the extent of the damage and accessibility.

A homeowner comfortable with basic electrical inspection can check whether the sensor wire connector has simply come loose and reseat it. However, resistance testing of the thermistor and tracing a wire break inside the indoor unit requires a multimeter and some familiarity with disassembling the indoor unit panel. If the sensor itself has failed, replacing it is generally a straightforward part swap but does require opening the unit.

A power reset may temporarily clear the displayed code, but E123 will return as soon as the control board re-reads the sensor signal and detects the same open or short condition. The underlying wiring or sensor fault must be physically corrected before the error will clear permanently.