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Error code reference

Samsung Air Conditioner Error Code E258

Fixed scroll compressor 3 discharge temperature sensor error (Open/Short)

Samsung codesSamsung air conditioner codes

Fixed scroll compressor 3 discharge temperature sensor error (Open/Short) - error level over 4.95V (-30C) or below 0.5V (151C).

First step from the service manual

Check the connection of fixed scroll compressor 3 discharge temperature sensor circuit; check for wire breaking.

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

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What E258 means on a Samsung air conditioner

Error code E258 on a Samsung air conditioner indicates a fault in the discharge temperature sensor circuit for fixed scroll compressor 3. This sensor monitors the temperature of refrigerant gas as it exits the compressor, which is a critical measurement for protecting the compressor from overheating and ensuring efficient system operation. The error is triggered when the sensor signal voltage falls outside the acceptable operating window: a reading above 4.95V corresponds to an out-of-range low temperature (approximately -30°C), while a reading below 0.5V corresponds to an out-of-range high temperature (approximately 151°C). Either condition is interpreted as an open or short circuit fault in the sensor or its wiring.

The fixed scroll compressor in a multi-compressor system is one of several compression stages, and its discharge temperature must be continuously monitored. When the control board receives a signal outside the 0.5V to 4.95V operating range, it cannot determine a valid temperature and will shut down or restrict operation to prevent potential compressor damage. The fault most commonly originates in the sensor wiring harness, connector terminals, or the sensor element itself rather than the compressor.

Diagnosis should begin by inspecting the sensor connector and wiring harness for any visible damage, corrosion, or loose connections. A broken wire or a disconnected plug can push the voltage reading to the upper limit (open circuit), while a short to ground or between wires can pull it below the lower threshold. If wiring checks out, the sensor resistance should be measured and compared against the expected temperature-resistance curve to determine whether the sensor element itself has failed.

Source: manufacturer service documentation.

Common causes of E258

  1. 01

    Broken or disconnected wiring

    Wiring / connection

    A broken wire or disconnected connector in the sensor circuit will cause the voltage signal to spike above 4.95V, registering as an open circuit. Carefully inspect the full length of the sensor harness and all connector pins for breaks, fraying, or pullout.

  2. 02

    Corroded or loose connector terminals

    Wiring / connection

    Moisture or vibration can cause terminal corrosion or looseness at the sensor plug, creating intermittent or total loss of signal. Check the connector body and individual pins for oxidation, bent contacts, or poor seating.

  3. 03

    Failed discharge temperature sensor

    Part replacement

    The sensor element itself can fail open or short internally, producing a voltage reading outside the 0.5V to 4.95V window even when wiring is intact. Measure the sensor resistance to determine if the element has degraded beyond its specified range.

  4. 04

    Short circuit in the sensor wiring

    Wiring / connection

    A wire shorted to ground or to another conductor in the harness will pull the signal voltage below 0.5V, triggering the low-voltage fault threshold. Inspect the harness for pinched sections, contact with sharp metal edges, or insulation damage.

  5. 05

    Control board input circuit fault

    Part replacement

    If the wiring and sensor both test within spec, the fault may lie in the control board's sensor input circuit, which processes the voltage signal. This is the least likely cause and should only be considered after all wiring and sensor checks are complete.

See the test procedure for each cause

Frequently asked questions about E258

What does E258 mean on a Samsung air conditioner?
E258 indicates an open or short circuit fault in the discharge temperature sensor for fixed scroll compressor 3. The control board has detected a sensor signal voltage either above 4.95V (corresponding to approximately -30°C) or below 0.5V (corresponding to approximately 151°C), both of which fall outside the valid operating range. The unit restricts or stops operation to protect the compressor until the fault is resolved.
Can I fix error E258 myself?
Some causes of E258, such as a loose connector or a visibly damaged wire, can be identified and addressed by a knowledgeable DIYer. However, working safely on a multi-compressor commercial or mini-split system requires familiarity with high-voltage circuits and refrigerant handling. If the sensor itself needs replacement or if the fault cannot be found at the wiring level, a qualified HVAC technician should perform the repair.
Is it safe to keep running my air conditioner with error E258 active?
No. The E258 fault means the system cannot monitor the discharge temperature of fixed scroll compressor 3, removing a key protection against compressor overheating. Continuing to operate the unit without a valid sensor reading risks serious and potentially irreversible compressor damage. The system should be serviced before returning to normal operation.
How much does it cost to repair error E258 on a Samsung air conditioner?
If only a wiring repair or connector cleaning is needed, labor costs may range from around $75 to $200 depending on access and time. If the discharge temperature sensor requires replacement, parts and labor combined typically range from $150 to $400. A control board replacement, if ultimately needed, can push total repair costs higher, often in the $400 to $900 range.
Will resetting the air conditioner clear error E258?
A reset may temporarily clear the error code from the display, but the fault will return immediately if the underlying wiring or sensor problem has not been corrected. Because E258 is triggered by a measurable out-of-range voltage condition, the control board will re-detect it as soon as the system restarts and reads the sensor signal again. A permanent fix requires repairing or replacing the faulty component.

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