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Error code reference

Daewoo Washer Error Code H4

Thermistor wash overheating error

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Thermistor wash overheating error - the heater worked without water in the tub, or the thermistor wash is defective or broken down.

First step from the service manual

Check the water level.

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

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What H4 means on a Daewoo washer

The H4 error code on a Daewoo washer indicates a thermistor wash overheating fault. This code is triggered when the wash heater element operates without an adequate water level in the tub, causing abnormally high temperatures that the thermistor detects as a safety threshold breach. The thermistor is a temperature-sensing resistor that monitors water temperature during the wash cycle. When it reads temperatures outside of the expected operating range, or when it cannot read accurately due to component failure, the control board interprets this as an overheating condition and halts the cycle.

There are two primary failure scenarios associated with H4. The first involves a low or absent water level in the tub, causing the heater to run dry and generate excessive heat. This is a condition that can permanently damage the heater element if not caught quickly. The second scenario involves a defective or failed wash thermistor itself. A broken thermistor may send incorrect resistance readings to the control board, falsely signaling an overheating event even when water levels and temperatures are normal.

Diagnosis should begin by confirming the water level in the tub at the time of the fault. If water supply appears normal, the thermistor should be tested for proper resistance values and inspected for visible damage, corrosion, or a broken connection. Water inlet components, including the inlet valve and pressure switch, should also be evaluated to confirm adequate water is reaching the drum before the heater activates.

Source: manufacturer service documentation.

Common causes of H4

  1. 01

    Insufficient water level in the tub

    Wiring / connection

    If the tub does not fill to the correct level before the heater activates, the element runs dry and generates extreme heat. Check that the water inlet valve is functioning and that water supply pressure is adequate.

  2. 02

    Defective wash thermistor

    Part replacement

    A failed or degraded thermistor sends inaccurate resistance readings to the control board, triggering a false overheating fault. The thermistor should be tested for correct resistance values and inspected for physical damage or corroded terminals.

  3. 03

    Faulty water inlet valve

    Part replacement

    A clogged or electrically failed inlet valve can prevent the tub from filling properly, leading the heater to activate without sufficient water present. Inspect the valve screens for debris and test the valve solenoid for proper electrical continuity.

  4. 04

    Pressure switch malfunction

    Part replacement

    The pressure switch signals the control board when the tub has reached the correct water level. A faulty pressure switch may incorrectly indicate that the tub is full, allowing the heater to run prematurely with low water levels.

  5. 05

    Failed or damaged heater element

    Part replacement

    If the heater element has been damaged by repeated dry-run conditions, it may overheat quickly even when water is present. Inspect the element for physical damage and test for proper electrical resistance.

See the test procedure for each cause

Frequently asked questions about H4

What does H4 mean on a Daewoo washer?
The H4 code on a Daewoo washer signals a thermistor wash overheating error. This occurs when the heater element operates without adequate water in the tub, or when the wash thermistor is defective or has failed. The machine stops the cycle automatically to prevent component damage. Checking the water level in the tub is the recommended first diagnostic step.
Can I fix the H4 error on my Daewoo washer myself?
Some causes of the H4 error are accessible to a knowledgeable DIYer. Verifying that the washer is filling with water properly and inspecting the inlet valve screens for clogs are straightforward checks. However, testing and replacing the thermistor, pressure switch, or heater element requires basic electrical diagnostic skills and a multimeter. If you are not comfortable working with electrical components, a professional technician is recommended.
Is it safe to continue using my washer when the H4 error appears?
You should not continue operating the washer while the H4 error is active. Running the heater without sufficient water can permanently damage the heating element and potentially cause additional heat-related damage to surrounding components. Address the root cause before resuming normal use.
How much does it cost to repair a Daewoo washer H4 error?
Repair costs depend on the failed component. A replacement thermistor is typically an inexpensive part, often in the range of $10 to $40. A water inlet valve may cost $20 to $60 in parts. A heater element replacement can range from $30 to $80 or more depending on availability. Adding professional labor, total repair costs can range from $75 to $200 or higher depending on the specific failure and your location.
Will resetting my Daewoo washer clear the H4 error code?
A reset may temporarily clear the H4 code, but if the underlying problem is not resolved, the error will return during the next wash cycle. Resetting is useful for ruling out a one-time sensor glitch, such as an isolated low water condition, but it is not a fix for a defective thermistor, failed inlet valve, or damaged heater. Always diagnose the cause before relying on a reset as a solution.

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