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Error code reference

Samsung Air Conditioner Error Code *D

Outdoor unit pipe sensor error (wired remote controller; * = indoor unit address).

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Outdoor unit pipe sensor error (wired remote controller; * = indoor unit address).

First step from the service manual

Check outdoor pipe sensor and outdoor unit PCB.

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

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  • Wiring diagram references and connector pinouts from the OEM service manual
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What *D means on a Samsung air conditioner

The *D error code on a Samsung air conditioner indicates an outdoor unit pipe sensor fault, detected and reported through the wired remote controller. The asterisk prefix corresponds to the specific indoor unit address in a multi-zone or centrally controlled system, allowing technicians to identify exactly which indoor unit's associated outdoor section is reporting the fault. The outdoor pipe sensor is a thermistor responsible for measuring refrigerant line temperature at the outdoor unit, and this data is used by the PCB to regulate compressor operation, defrost cycles, and refrigerant flow management.

This error is triggered when the outdoor unit PCB receives a signal from the pipe sensor that falls outside the expected resistance or voltage range. A properly functioning thermistor will read a predictable resistance curve corresponding to refrigerant pipe temperature. If the sensor reads an open circuit, a short circuit, or a grossly out-of-range resistance value, the PCB flags the fault and halts or limits operation to protect the system from running in an uncontrolled thermal state.

The two primary diagnostic targets are the outdoor pipe sensor itself and the outdoor unit PCB. The sensor should be inspected for physical damage, corrosion at the connector, or wire harness chafing. The connector pins should be checked for secure seating and continuity. If the sensor checks out within specification, the PCB input circuit for the sensor signal must be evaluated, as a failed input stage on the board can misread a healthy sensor and generate a false fault.

Source: manufacturer service documentation.

Common causes of *D

  1. 01

    Faulty or failed outdoor pipe sensor

    Part replacement

    The thermistor sensor itself has degraded, shorted, or opened internally, causing it to report an out-of-range resistance value. Resistance testing across the sensor terminals will reveal a reading that does not match the expected temperature-resistance curve.

  2. 02

    Loose or corroded sensor connector

    Wiring / connection

    Vibration or moisture intrusion can cause the sensor's wiring connector to loosen or corrode at the outdoor PCB or sensor terminals, creating an intermittent or open circuit signal. Visually inspect the connector for corrosion, bent pins, or incomplete seating.

  3. 03

    Damaged sensor wiring harness

    Part replacement

    The wire running from the outdoor pipe sensor to the PCB may be chafed, pinched, or broken, especially near routing points along the outdoor unit cabinet. A continuity test along the harness will identify an open or shorted conductor.

  4. 04

    Outdoor unit PCB input circuit failure

    Part replacement

    If the sensor and its wiring test correctly, the PCB's sensor input stage may have failed, causing it to misinterpret a good sensor signal as a fault. This requires evaluating the board's input voltage and signal processing circuit.

  5. 05

    Incorrect indoor unit address configuration

    Wiring / connection

    In multi-zone systems, a misconfigured indoor unit address can cause the remote controller to associate sensor data with the wrong unit, triggering a false *D code. Verify that indoor unit addressing matches the system wiring and controller settings.

See the test procedure for each cause

Frequently asked questions about *D

What does *D mean on a Samsung air_conditioner?
The *D code indicates an outdoor unit pipe sensor error reported through the wired remote controller. The asterisk represents the address of the specific indoor unit associated with the fault. The outdoor pipe sensor is a thermistor that monitors refrigerant line temperature at the outdoor unit, and this error means the outdoor PCB is detecting a signal from that sensor that is outside acceptable parameters. Diagnosis should start with the outdoor pipe sensor and the outdoor unit PCB.
Can I fix the *D error on my Samsung air conditioner myself?
Basic checks such as inspecting the sensor connector for looseness or corrosion and verifying wiring harness integrity can be performed by a knowledgeable DIYer with basic electrical tools. However, resistance-testing the thermistor sensor, evaluating the PCB input circuit, and replacing refrigerant-side components typically require technical knowledge and access to service equipment. If the fault involves the PCB or refrigerant system, a qualified HVAC technician should handle the repair.
Is it safe to keep running my Samsung air conditioner with the *D error active?
Operating the system while the *D error is active is not recommended. The outdoor pipe sensor provides critical temperature data that the control board uses to regulate compressor operation and defrost cycles. Running without accurate sensor input could lead to improper refrigerant management or compressor damage over time. The system may already be limiting or halting operation as a protective measure.
Will resetting my Samsung air conditioner clear the *D error?
A power reset may temporarily clear the error code, but if the underlying cause such as a failed sensor, damaged wiring, or faulty PCB is still present, the code will return once the system restarts and the PCB re-evaluates the sensor signal. A reset alone does not fix the root problem and should not be used as a substitute for proper diagnosis and repair.
How much does it cost to repair a *D outdoor pipe sensor error on a Samsung air conditioner?
Repair costs vary depending on the root cause. Replacing the outdoor pipe sensor is generally the least expensive fix, with parts typically ranging from $20 to $80 and labor adding to that depending on the technician's rates in your area. If the outdoor unit PCB has failed, costs can range significantly higher, often between $150 and $600 or more for parts and labor combined. Getting a diagnostic assessment from a certified technician is the best way to get an accurate estimate for your specific situation.

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