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Error code reference

Samsung Air Conditioner Error Code 258

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 connection part of fixed scroll compressor 3 discharge temp sensor circuit; check 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 258 means on a Samsung air conditioner

Samsung error code 258 indicates a fault in the discharge temperature sensor circuit associated with fixed scroll compressor 3. This sensor monitors the refrigerant discharge temperature at the outlet of the compressor scroll assembly, which is a critical data point for protecting the compressor from overheating and ensuring efficient system operation. The error is triggered when the sensor signal voltage falls outside an acceptable operating range: a reading above 4.95V corresponds to an open circuit condition (indicating an approximate temperature below -30C), while a reading below 0.5V indicates a short circuit condition (corresponding to a temperature above 151C). Both extremes represent fault states rather than actual temperature readings, and the control board flags error 258 when either threshold is exceeded.

The most likely causes involve the physical sensor circuit rather than the compressor itself. A broken wire or damaged harness in the sensor circuit can cause an open condition, pushing voltage above the upper threshold. A short to ground in the wiring or a failed sensor with internal resistance collapse can drive voltage below the lower threshold. The connector between the sensor harness and the PCB is also a common failure point, particularly in systems exposed to vibration, moisture, or thermal cycling. The diagnostic process should begin with a thorough visual inspection of the sensor wiring, connector pins, and PCB terminal contacts before condemning the sensor or any other component.

Source: manufacturer service documentation.

Common causes of 258

  1. 01

    Broken or damaged sensor wire

    Wiring / connection

    A broken conductor in the sensor harness causes an open circuit, pushing the signal voltage above 4.95V. Inspect the full length of the wiring from the sensor to the PCB for cuts, pinches, or fatigue cracks near connectors.

  2. 02

    Loose or corroded connector

    Wiring / connection

    A poorly seated or corroded connector at the PCB or sensor end can intermittently or permanently interrupt the signal circuit. Check that connector pins are fully engaged, free of oxidation, and not bent or backed out of their housing.

  3. 03

    Failed discharge temperature sensor

    Part replacement

    The sensor itself can fail in either an open or shorted state, producing a voltage reading outside the 0.5V to 4.95V window. If wiring and connectors check out, measure sensor resistance and compare it to expected values at a known ambient temperature.

  4. 04

    Short circuit in sensor wiring

    Wiring / connection

    Wiring that has chafed against a metal edge or been pinched during installation can short to ground, pulling the signal voltage below 0.5V. Look for any areas where the harness contacts the unit chassis or refrigerant lines.

  5. 05

    Faulty or damaged PCB connector terminal

    Part replacement

    The PCB header that accepts the sensor connector can have damaged, corroded, or pushed-back pins that prevent a reliable electrical connection. If the harness connector is in good condition but the fault persists, inspect the PCB-side terminal closely.

See the test procedure for each cause

Frequently asked questions about 258

What does 258 mean on a Samsung air conditioner?
Error 258 indicates a fault in the discharge temperature sensor circuit for fixed scroll compressor 3. The control board has detected a signal voltage either above 4.95V (open circuit, below -30C) or below 0.5V (short circuit, above 151C). Both conditions indicate an electrical fault in the sensor circuit rather than an actual extreme temperature reading. The system flags this error to prevent compressor damage from unmonitored discharge temperatures.
Can I fix error 258 myself, or do I need a technician?
Some aspects of this repair are accessible to a knowledgeable DIYer. Checking the sensor wiring for visible damage, reseating the connector, and cleaning corroded terminals are straightforward tasks. However, if the sensor itself needs to be replaced or the fault is traced to the PCB, a qualified HVAC technician with the proper tools and refrigerant handling certification should complete the repair.
Is error 258 on a Samsung air conditioner a safety concern?
Yes, this error should be addressed promptly. The discharge temperature sensor protects compressor 3 from overheating by giving the control board real-time data about refrigerant conditions at the compressor outlet. If the sensor circuit is faulty, the system cannot reliably monitor this critical parameter, which could allow the compressor to operate under unsafe thermal conditions. The unit is right to limit or halt operation until the fault is cleared.
Will resetting the air conditioner clear error 258?
A power reset may temporarily clear the error code, but it will return if the underlying wiring or sensor fault is not repaired. Because the fault is hardware-based, the control board will detect the out-of-range voltage signal again as soon as the unit restarts and attempts to read the sensor. A reset alone is not a fix and should only be used as part of a diagnostic process.
How much does it cost to repair error 258 on a Samsung air conditioner?
Repair costs vary depending on the root cause. If the issue is a loose or corroded connector that only requires cleaning and reseating, labor costs may be the primary expense, typically in the range of $75 to $150 for a service call. If the discharge temperature sensor itself needs replacement, parts and labor combined generally range from $150 to $350. If the PCB connector or board requires replacement, costs can be higher, often $300 to $600 or more depending on the unit and parts availability.

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