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Error code reference

Daewoo Microwave Error Code Er01

Humidity sensor error during auto reheating operation

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Humidity sensor error during auto reheating operation - sensor circuit voltage out of expected range.

First step from the service manual

Check humidity sensor connection to CN3, verify resistors R6-R10, and check voltage at points A (0.5V-3.5V), B (11.3VDC), C (4.4VDC), D (2.2VDC) after 1-2 minutes of auto reheating operation.

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

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What Er01 means on a Daewoo microwave

The Er01 error code on a Daewoo microwave indicates a humidity sensor circuit fault detected during auto reheating operation. The humidity sensor monitors moisture levels released by food during cooking, allowing the microwave to automatically determine when reheating is complete. When the sensor circuit voltage falls outside the expected operating range, the control board flags Er01 and halts normal auto-reheat function. This is a circuit-level fault, meaning the issue may lie in the sensor itself, its wiring connections, or the associated resistor network on the control board.

Diagnosis begins at connector CN3, which carries the humidity sensor signal to the control board. Four test points define the expected voltage profile after 1 to 2 minutes of auto reheating operation: point A should read between 0.5V and 3.5V (the variable sensor signal), point B should read 11.3VDC, point C should read 4.4VDC, and point D should read 2.2VDC. Resistors R6 through R10 form the signal conditioning network for the sensor circuit, and a failed or out-of-tolerance resistor in this group can shift voltages at any of these test points outside acceptable limits.

The most common causes include a loose or corroded connection at CN3, sensor contamination from grease or steam buildup on the sensor element, and component failure in the R6-R10 resistor network. Because the fault is tied specifically to auto reheating mode, standard timed cooking may still function normally even when Er01 is active. Systematic voltage checks at the four test points will isolate whether the fault originates in the sensor, the wiring, or the board-level resistor network.

Source: manufacturer service documentation.

Common causes of Er01

  1. 01

    Loose or faulty CN3 connector

    Wiring / connection

    The humidity sensor connects to the control board through connector CN3. A loose, corroded, or damaged connection here will disrupt the sensor signal and cause voltage readings at test points A through D to fall outside expected ranges.

  2. 02

    Contaminated or failed humidity sensor

    Part replacement

    Grease, steam residue, or physical damage to the sensor element can cause it to output an incorrect signal voltage at point A, which should read between 0.5V and 3.5V during auto reheat operation. A sensor reading consistently outside this window likely requires replacement.

  3. 03

    Failed resistor in R6-R10 network

    Part replacement

    Resistors R6 through R10 condition the sensor signal before it reaches the control board. A failed or drifted resistor in this group will cause one or more of the fixed reference voltages at points B, C, or D to read incorrectly, triggering Er01.

  4. 04

    Damaged sensor wiring harness

    Part replacement

    The wiring between the humidity sensor and CN3 can develop breaks or shorts due to heat exposure over time. Inspect the full length of the harness for burned, pinched, or frayed sections that could interrupt the sensor signal.

  5. 05

    Control board failure

    Part replacement

    If all four test point voltages are correct and the CN3 connection is secure, the fault may lie in the control board circuit that processes the sensor signal. Board-level failure is the least common cause and should only be considered after all other components are ruled out.

See the test procedure for each cause

Frequently asked questions about Er01

What does Er01 mean on a Daewoo microwave?
Er01 indicates a humidity sensor error that occurs during auto reheating operation. The sensor circuit voltage has gone outside the expected range, preventing the microwave from using its automatic moisture-detection feature. The fault is tied to the sensor circuit connected at CN3 on the control board, along with the associated R6-R10 resistor network.
Can I fix the Er01 error myself?
A knowledgeable DIYer can start by inspecting and reseating the CN3 connector, cleaning the humidity sensor, and visually checking the wiring harness for damage. Voltage testing at points A, B, C, and D requires a multimeter and basic electronics knowledge. Resistor replacement or control board repair typically requires soldering skills and may be better handled by a qualified technician.
Will resetting the microwave clear the Er01 code?
Unplugging the microwave and restoring power may temporarily clear the code, but Er01 will return whenever auto reheating mode is activated if the underlying sensor circuit fault has not been corrected. The code is triggered by an out-of-range voltage condition, so it will persist until the root cause is repaired.
Is it safe to use my Daewoo microwave while Er01 is displayed?
Standard timed cooking functions may still operate normally when Er01 is active, since the error is specific to the auto reheating mode. However, the auto-reheat feature should not be relied upon until the fault is resolved, as the microwave cannot accurately detect when food has reached the appropriate temperature in this mode. If the display shows Er01 continuously or the unit behaves erratically, stop using it and have it inspected.
How much does it cost to repair an Er01 error on a Daewoo microwave?
Repair costs vary depending on the faulty component. Reconnecting or replacing the CN3 harness is generally the least expensive fix, typically in the range of a service call fee plus minimal parts cost. Humidity sensor replacement parts and resistor network repairs tend to fall in a moderate cost range, while control board replacement is the most expensive option and may approach or exceed the value of an older unit.

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