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Error code reference

LG Microwave Error Code E-B3

Humidity sensor max time error.

LG codesLG microwave codes

Humidity sensor max time error.

First step from the service manual

Check sensor.

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

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What E-B3 means on a LG microwave

The E-B3 error code on an LG microwave indicates a humidity sensor maximum time error. This means the humidity sensor, which monitors steam and moisture levels inside the cavity during cooking, has exceeded its allowable detection time limit without completing its expected cycle. The control board tracks how long the sensor operates during a cooking function, and when that duration surpasses a preset threshold without the sensor signaling completion, the E-B3 fault is triggered and cooking is interrupted.

The humidity sensor in LG microwaves works by detecting moisture vapor released from food during heating. As food cooks, steam rises and the sensor registers increasing humidity levels, which the control board uses to determine doneness and adjust cooking time automatically. If the sensor cannot detect the expected rise in humidity within the allowed window, or if it sends a continuous or erratic signal that never resolves, the board interprets this as a fault condition.

Common causes include a failed or degraded humidity sensor, poor electrical connections at the sensor harness, or contamination on the sensor surface from food splatter or grease buildup. In some cases, the control board itself may be unable to correctly interpret the sensor signal. The first diagnostic step is to inspect and test the sensor directly, checking its wiring connections and physical condition before moving to component replacement.

Source: manufacturer service documentation.

Common causes of E-B3

  1. 01

    Failed or degraded humidity sensor

    Part replacement

    The humidity sensor itself may have worn out or failed internally, causing it to send no signal or an incorrect signal to the control board. Testing the sensor for proper continuity and output is the primary diagnostic step.

  2. 02

    Contaminated sensor surface

    Wiring / connection

    Grease, food splatter, or residue can coat the humidity sensor and interfere with its ability to detect moisture accurately. Inspect the sensor surface for visible buildup and clean carefully if contamination is present.

  3. 03

    Loose or damaged sensor wiring harness

    Wiring / connection

    A loose connector or damaged wire between the humidity sensor and the control board can interrupt the signal, causing a timing fault. Inspect all connectors at the sensor and trace the harness for any pinched or frayed wiring.

  4. 04

    Faulty control board

    Part replacement

    If the sensor and its wiring check out correctly, the control board may be failing to process the sensor signal within the expected time parameters. This is less common but should be considered after all other components are ruled out.

See the test procedure for each cause

Frequently asked questions about E-B3

What does E-B3 mean on a LG microwave?
The E-B3 code on an LG microwave indicates a humidity sensor maximum time error. The humidity sensor, which detects steam levels during cooking to help regulate cook time, exceeded the maximum allowed operating duration without completing its cycle. The microwave stops cooking and displays this code to alert you that the sensor circuit needs to be inspected.
Can I fix the E-B3 error on my LG microwave myself?
Some causes of E-B3 are DIY-friendly, such as cleaning a contaminated sensor surface or reseating a loose wiring connector at the sensor. However, replacing the humidity sensor or the control board involves working inside the microwave cabinet, which requires discharging the high-voltage capacitor before any work begins. If you are not comfortable with high-voltage appliance repair, a qualified technician should perform the repair.
Is it safe to use my LG microwave while it is showing the E-B3 error?
You should not continue using the microwave while the E-B3 error is active. The fault indicates the humidity sensor is not functioning correctly, which means the microwave may not properly regulate cooking cycles. Operating the unit in this condition could lead to overcooking, unpredictable behavior, or further component damage.
How much does it cost to repair an E-B3 error on an LG microwave?
Repair costs vary depending on the faulty component. A replacement humidity sensor typically ranges from around 20 to 60 dollars for the part, while a control board can range from 80 to 200 dollars or more. Adding professional labor costs, a full repair visit may run anywhere from 100 to 300 dollars depending on your location and the parts required.
Will resetting my LG microwave clear the E-B3 error code?
Unplugging the microwave for a few minutes and restoring power may temporarily clear the E-B3 code, but if the underlying cause such as a faulty sensor or wiring issue is not resolved, the error will return during the next cooking cycle that uses the humidity sensor function. A reset alone is not a fix and should only be used as part of the diagnostic process.

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