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Error code reference

LG Microwave Error Code E-34

Weight Sensor error

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Weight Sensor error - initial value of K calculated by weight sensor is above and under ±28 as value of HEX.

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

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What E-34 means on a LG microwave

The E-34 error code on an LG microwave indicates a Weight Sensor fault. Specifically, the error triggers when the initial calibration value, referred to as K, falls outside the acceptable tolerance range of plus or minus 28 in hexadecimal (HEX) units. This K value is a baseline measurement the weight sensor calculates during its startup or initialization sequence. When the sensor's output drifts too far above or below that acceptable window, the microwave's control system flags the condition as a calibration error and halts normal operation.

The weight sensor in LG microwaves is part of the automatic cooking system. It measures the mass of food placed inside the cavity and uses that data to adjust cooking time and power levels automatically. The sensor assembly typically includes a load cell or piezoelectric element connected to a control board. If the sensor's resting output, measured before any load is applied, is already outside the acceptable HEX range, the microwave cannot establish a reliable baseline for cooking calculations, which is why it throws the E-34 fault.

Common causes include physical damage to the sensor, contamination such as food debris or moisture around the sensor mounting area, a loose or corroded wiring harness connection between the sensor and the control board, or internal failure of the sensor element itself. In some cases, mechanical stress on the microwave cavity floor or turntable assembly can place unintended load on the sensor, skewing its initial reading. The first diagnostic step is a thorough inspection of the weight sensor and its connections.

Source: manufacturer service documentation.

Common causes of E-34

  1. 01

    Contamination around the weight sensor

    Wiring / connection

    Food debris, grease, or moisture around the sensor mounting area can interfere with its ability to produce an accurate resting reading. Inspect and clean the sensor area thoroughly, paying attention to the cavity floor and any seams near the sensor.

  2. 02

    Loose or corroded wiring harness connection

    Wiring / connection

    A poor electrical connection between the weight sensor and the control board can cause erratic or out-of-range K values. Unplug the microwave, then inspect the sensor connector pins for corrosion, bent contacts, or incomplete seating.

  3. 03

    Failed weight sensor element

    Part replacement

    The internal load cell or sensing element inside the weight sensor can fail and produce a signal that is permanently outside the acceptable HEX range. If cleaning and reseating connectors do not resolve the fault, the sensor unit likely needs replacement.

  4. 04

    Mechanical stress on the sensor

    Wiring / connection

    A warped turntable support, an object resting on the cavity floor, or physical impact to the microwave can place unintended mechanical load on the sensor, causing its initial value to read incorrectly. Check that nothing is pressing on or lodged beneath the turntable plate or support ring.

  5. 05

    Faulty main control board

    Part replacement

    If the control board is not correctly reading or processing the signal from the weight sensor, it may generate an E-34 fault even when the sensor itself is functioning properly. This is the least likely cause and should be considered only after the sensor and wiring have been ruled out.

See the test procedure for each cause

Frequently asked questions about E-34

What does E-34 mean on a LG microwave?
E-34 indicates a Weight Sensor error. The microwave calculates an initial calibration value called K when the weight sensor initializes, and E-34 appears when that value falls outside the acceptable range of plus or minus 28 in hexadecimal units. This means the sensor cannot establish a reliable baseline, so the microwave stops normal operation. The weight sensor is used to automatically adjust cooking time and power based on food mass.
Can I fix the E-34 error myself?
Some causes of E-34 can be addressed without professional help. Start by unplugging the microwave and inspecting the area around the weight sensor for food debris, moisture, or grease, then clean it thoroughly. Also check that the turntable and its support ring are seated correctly and that nothing is pressing on the cavity floor. If those steps do not clear the fault, the sensor wiring connections or the sensor itself may need replacement, which is more involved.
Will resetting the microwave clear the E-34 error?
A simple power reset by unplugging the unit for a few minutes may temporarily clear the display, but if the underlying sensor issue remains, the E-34 code will return when the microwave attempts to initialize the weight sensor again. A lasting fix requires addressing the root cause, whether that is contamination, a loose connection, or a faulty sensor component.
Is it safe to use my LG microwave while it shows E-34?
It is not recommended to continue using the microwave while E-34 is active. The error indicates the weight sensor cannot calibrate correctly, which means the automatic cooking functions cannot operate reliably. Beyond inaccurate cooking results, operating an appliance with an unresolved sensor fault can sometimes mask other developing issues. Address the error before resuming regular use.
How much does it cost to repair an E-34 error on an LG microwave?
Repair costs vary depending on the root cause. If the fix is simply cleaning the sensor area or reseating a connector, there is no parts cost involved. If the weight sensor element needs replacement, parts typically range from around 20 to 80 dollars depending on the model, with professional labor adding 75 to 150 dollars or more. A control board replacement, if needed, is the most expensive scenario and could bring total costs close to or exceeding the value of an older unit.

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