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Error code reference

Sub-Zero Freezer Error Code 43

Check Left Refrigerant Valve and Wiring.

Sub-Zero codesSub-Zero freezer codes

Check Left Refrigerant Valve and Wiring.

First step from the service manual

Check the Aweco dual refrigerant valve and wiring (295 ohms).

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 43 means on a Sub-Zero freezer

Error code 43 on a Sub-Zero freezer indicates a fault detected in the left refrigerant valve circuit. This valve is an Aweco dual refrigerant valve, and the control board monitors its electrical characteristics to confirm proper operation. When the measured resistance deviates significantly from the expected specification of 295 ohms, or when the wiring circuit is open or shorted, the board flags this error to prevent improper refrigerant routing that could compromise cooling performance.

The Aweco dual refrigerant valve controls the flow of refrigerant between the two sealed system circuits in Sub-Zero units that use a dual refrigeration design. If this valve fails electrically or mechanically, one or both compartments may lose the ability to maintain proper temperature. The left valve designation refers specifically to the valve associated with the left cooling circuit, and its coil winding must measure at or near 295 ohms to be considered within spec.

Common causes of this fault include a burned or open coil in the valve itself, corrosion or damage at the wiring harness connectors, chafed or broken wiring between the valve and control board, or in some cases a failed control board that cannot accurately read the valve resistance. Diagnosis should begin with a resistance check across the valve coil terminals using a multimeter, comparing the reading to the 295-ohm specification. Wiring continuity and connector integrity should be inspected before condemning the valve itself.

Source: manufacturer service documentation.

Common causes of 43

  1. 01

    Failed Aweco valve coil

    Part replacement

    The coil winding inside the dual refrigerant valve can burn out or open, causing resistance to read far outside the expected 295-ohm range. Measure resistance directly across the valve coil terminals to confirm.

  2. 02

    Damaged or corroded wiring harness connectors

    Wiring / connection

    Corrosion or physical damage at the connector between the valve and the control board can interrupt the circuit or introduce high resistance. Inspect connectors closely for green corrosion, bent pins, or loose seating.

  3. 03

    Broken or chafed wire in the valve circuit

    Wiring / connection

    Wiring routed near sharp edges or moving components can develop breaks or shorts over time. A continuity test along the full wire run from the control board to the valve will identify any open or shorted section.

  4. 04

    Intermittent valve connection due to vibration

    Wiring / connection

    Compressor vibration can loosen connectors over years of operation, causing intermittent contact that triggers the fault code. Reseating all connectors in the valve circuit may resolve the error if no physical damage is present.

  5. 05

    Control board misreading the valve circuit

    Part replacement

    In less common cases, the control board itself may be faulty and unable to accurately measure or respond to the valve's resistance signal. This should only be considered after the valve and all wiring have been confirmed to be within specification.

See the test procedure for each cause

Frequently asked questions about 43

What does 43 mean on a Sub-Zero freezer?
Error code 43 means the control board has detected a problem with the left refrigerant valve or its wiring circuit. This valve, made by Aweco, controls refrigerant flow in the left cooling circuit and should measure approximately 295 ohms at its coil terminals. The fault indicates the valve or wiring is outside acceptable parameters.
Can I fix error code 43 on my Sub-Zero freezer myself?
Basic wiring inspection and connector reseating are tasks a knowledgeable DIYer can perform, but testing the valve coil resistance requires a multimeter and familiarity with the wiring harness layout. Replacing the Aweco dual refrigerant valve involves working near sealed system components, so full valve replacement is best handled by a certified technician. Attempting repairs without proper knowledge can void warranties or cause additional damage.
Is it safe to continue using my Sub-Zero freezer when error code 43 is displayed?
A faulty refrigerant valve can cause the freezer to lose its ability to maintain safe storage temperatures, which creates a food safety risk. It is not recommended to rely on the unit for storing perishables until the fault is diagnosed and repaired. Monitor internal temperatures closely if you must use the freezer briefly before service.
How much does it cost to repair error code 43 on a Sub-Zero freezer?
If only wiring or a connector needs repair, costs are generally in the range of $100 to $250 including labor. Replacing the Aweco dual refrigerant valve typically costs between $200 and $500 or more depending on parts availability and labor rates in your area. A control board replacement, if required, can add additional cost to the repair.
Will resetting my Sub-Zero freezer clear error code 43?
A reset may temporarily clear the code, but it will return if the underlying fault in the valve or wiring has not been corrected. Resetting without repairing the root cause does not restore proper valve operation and can delay a necessary repair while the freezer continues to underperform. The fault should be diagnosed and resolved before relying on the unit.

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