Samsung Air Conditioner Error Code E312

E312 indicates an open or short circuit fault in the Sump Temperature Fixed 1 sensor circuit on the outdoor unit. The error is triggered when the outdoor temperature is above -10°C and the sensor is returning a signal outside the acceptable resistance range. The system uses this sensor to monitor sump temperature and protect the compressor. The fault must be resolved before normal operation can resume.

It is not recommended to continue running the unit with an E312 fault active. The sump temperature sensor provides critical data used to protect the compressor from overheating or operating under abnormal conditions. Running the system without a valid sensor signal risks compressor damage, which is significantly more expensive to repair than the sensor itself.

A power reset may temporarily clear the error code if the fault is intermittent, such as a connector that is partially seated. However, if the sensor or wiring has a genuine open or short circuit fault, the E312 code will return as soon as the unit restarts and the control board re-evaluates the sensor input. A reset should only be used as a diagnostic step, not as a substitute for identifying and correcting the underlying cause.

Start by powering down the unit and inspecting the sensor connector at the outdoor PCB to make sure it is fully seated. Next, use a multimeter to measure the resistance of the sump temperature sensor and compare the reading to the expected value for the current ambient temperature. If the sensor reads open or shorted, replace the sensor. If the sensor reads correctly, inspect the wiring harness for damage and, as a last step, consider replacing the outdoor PCB.

If the fix is simply reseating a loose connector, there may be no parts cost, though a service call fee typically ranges from $75 to $150. Replacing the sump temperature sensor itself generally costs between $20 and $80 for the part, plus labor. If the outdoor PCB requires replacement, total repair costs can range from $250 to $600 or more depending on the model and local labor rates.