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Error code reference

Samsung Air Conditioner Error Code E231

COND_OUT main temperature sensor error (Open/Short)

Samsung codesSamsung air conditioner codes

COND_OUT main temperature sensor error (Open/Short) - error level over 4.9V (-50C) or below 0.4V (93C).

First step from the service manual

Check the connection of COND OUT temperature sensor circuit; check for wire breaking and connector PCB connection status.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What E231 means on a Samsung air conditioner

The E231 error code on a Samsung air conditioner indicates a fault in the COND_OUT (condenser outlet) main temperature sensor circuit. This sensor monitors the refrigerant temperature at the outlet of the condenser coil, which is critical data the control board uses to manage compressor operation, fan speed, and overall system efficiency. The error triggers when the sensor signal voltage falls outside the acceptable operating range: a reading over 4.9V corresponds to an open circuit condition (interpreted as approximately -50 degrees Celsius), while a reading below 0.4V indicates a short circuit condition (interpreted as approximately 93 degrees Celsius). Neither extreme represents an actual refrigerant temperature, so the control board flags the signal as invalid and halts normal operation.

The COND_OUT sensor is a negative temperature coefficient (NTC) thermistor that changes resistance in response to temperature. When the circuit is open, the thermistor or its wiring has lost continuity, driving the voltage signal to its upper rail. When shorted, resistance drops to near zero, pulling the signal voltage to its lower rail. Both conditions produce readings the PCB cannot use for safe system control, which is why the error level thresholds are defined at those voltage boundaries.

The primary diagnostic path starts with a physical inspection of the sensor wiring harness and connector. Technicians should check for broken wires, corrosion at the connector pins, and proper seating of the connector on the PCB. If wiring is intact, the sensor itself should be tested for resistance at a known temperature and compared against the manufacturer's NTC curve to determine whether the thermistor has failed internally.

Source: manufacturer service documentation.

Common causes of E231

  1. 01

    Loose or disconnected sensor connector

    Wiring / connection

    The sensor connector may have vibrated loose from the control PCB or from the sensor harness itself. Check that the connector is fully seated and that no pins are bent or pushed back.

  2. 02

    Broken or damaged sensor wiring

    Part replacement

    The wiring harness running to the COND_OUT sensor can develop breaks due to vibration, pinching, or physical damage over time. Inspect the full length of the harness for cuts, chafing, or bare conductors that could cause an open or short circuit.

  3. 03

    Corroded or contaminated connector pins

    Wiring / connection

    Moisture exposure can cause corrosion at the connector pins, increasing resistance in the circuit and pushing the signal voltage out of range. Inspect both the sensor-side and PCB-side connector terminals for oxidation or residue.

  4. 04

    Failed COND_OUT temperature sensor

    Part replacement

    The NTC thermistor inside the sensor can fail internally, resulting in either an open circuit or a fixed resistance that does not change with temperature. If wiring and connectors check out, measure the sensor resistance and compare it to the expected value at the current ambient temperature.

  5. 05

    Faulty control PCB

    Part replacement

    If the sensor and all wiring test within specification but the error persists, the input circuit on the main control PCB may have failed. This is the least likely cause and should only be considered after all other components have been ruled out.

See the test procedure for each cause

Frequently asked questions about E231

What does E231 mean on a Samsung air conditioner?
E231 indicates a fault in the COND_OUT main temperature sensor circuit at the condenser outlet. The control board has detected a signal voltage either above 4.9V (open circuit, reading as -50 degrees Celsius) or below 0.4V (short circuit, reading as 93 degrees Celsius). Because neither value is a valid operating temperature, the unit stops running to protect the system. The root cause is typically a wiring, connector, or sensor failure.
Can I fix the E231 error myself?
Some causes of E231 are accessible to a knowledgeable DIYer. Checking the sensor connector for loose seating, inspecting the wiring harness for visible damage, and cleaning corroded terminals are tasks that do not require special tools. However, testing sensor resistance accurately requires a multimeter and knowledge of NTC thermistor values, and replacing a control PCB involves working near high-voltage components, which should be left to a certified technician.
Is it safe to keep using my air conditioner with the E231 error?
No. When E231 is active, the unit lacks reliable condenser outlet temperature data, which means the control board cannot properly protect the compressor from overheating or refrigerant pressure extremes. Operating the system in this condition risks compressor damage and potentially costly repairs. The unit should remain off until the sensor circuit is repaired.
Will resetting the air conditioner clear the E231 error?
A power reset may temporarily clear the error display, but if the underlying sensor circuit fault still exists, the E231 code will return once the unit attempts to operate and re-reads the invalid signal. A reset alone is not a fix. The wiring, connector, and sensor must be inspected and repaired before the error will stay clear.
How much does it cost to repair an E231 error on a Samsung air conditioner?
Repair costs depend on what component has failed. Reconnecting a loose connector or cleaning corroded pins may cost nothing beyond a service call fee, which typically ranges from $75 to $150. Replacing the COND_OUT temperature sensor is generally inexpensive, with parts usually in the $15 to $50 range plus labor. If the control PCB is at fault, total costs including parts and labor can range from $200 to $600 or more depending on the unit model.

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