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Error code reference

LG Microwave Error Code E-29

Sensor open error (referenced in troubleshooting flow for sensor open errors).

LG codesLG microwave codes

Sensor open error (referenced in troubleshooting flow for sensor open errors).

First step from the service manual

Check if sensor housing is inserted into the connector of the main PCB.

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

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What E-29 means on a LG microwave

The E-29 error code on an LG microwave indicates a sensor open error, meaning the control system has detected an open circuit condition in the humidity or cooking sensor circuit. In a properly functioning unit, the sensor provides a continuous electrical signal to the main PCB that allows the microwave to monitor moisture levels and adjust cooking cycles accordingly. When that circuit is broken or interrupted, the main PCB cannot receive a valid signal and triggers the E-29 fault to prevent incorrect cooking behavior.

The most common root cause is a physical disconnection between the sensor housing and its connector on the main PCB. The sensor assembly is a discrete component that plugs into a dedicated port on the board, and vibration, improper reassembly after a prior repair, or a loose factory connection can cause the housing to back out of the connector. This is why the first diagnostic step is a direct physical inspection of that connection point before any electrical testing is performed.

If the connector is seated correctly and the error persists, the fault may lie within the sensor itself, which has developed an internal open circuit, or in the wiring harness between the sensor and the board. A failed sensor will present an open circuit when measured with a multimeter across its terminals. The main PCB is a less likely but possible cause if the connector receptacle is damaged or the board circuitry reading the sensor signal has failed.

Source: manufacturer service documentation.

Common causes of E-29

  1. 01

    Disconnected sensor housing connector

    Wiring / connection

    The sensor housing plug has backed out of or was never fully seated into its connector on the main PCB. Visually inspect the connector and press the housing firmly into place to confirm a secure fit.

  2. 02

    Failed or open-circuit sensor

    Part replacement

    The sensor itself has developed an internal open circuit and can no longer pass a signal. Testing across the sensor terminals with a multimeter will show no continuity if the sensor has failed internally.

  3. 03

    Damaged or broken wiring harness

    Part replacement

    The wiring between the sensor and the main PCB may have a broken wire or corroded terminal, interrupting the circuit. Inspect the harness for visible damage, pinching, or corrosion at the connector pins.

  4. 04

    Damaged connector receptacle on main PCB

    Part replacement

    The connector port on the main PCB may have bent pins or physical damage that prevents the sensor housing from making proper contact. Inspect the board-side connector carefully under good lighting.

See the test procedure for each cause

Frequently asked questions about E-29

What does E-29 mean on a LG microwave?
E-29 is a sensor open error, meaning the main PCB has detected an open or broken circuit in the sensor connection. The microwave cannot receive a valid signal from the sensor, so it stops normal operation and displays this code. The first thing to check is whether the sensor housing is fully inserted into its connector on the main PCB.
Can I fix the E-29 error myself?
If the sensor housing has simply become unplugged, reseating it into the main PCB connector may resolve the error without any parts or specialized tools. If the sensor itself has failed or the wiring harness is damaged, replacing those components requires basic electrical knowledge and comfort working inside the microwave cabinet. Always discharge the high-voltage capacitor before working inside any microwave.
Is it safe to use my LG microwave while it shows E-29?
It is not recommended to continue using the microwave while this error is active. The sensor open condition means the unit cannot properly monitor cooking conditions, which could result in overcooking, undercooked food, or unintended operation. Address the fault before resuming normal use.
Will resetting the microwave clear the E-29 error?
A power reset by unplugging the unit for a few minutes may temporarily clear the error code, but it will return if the underlying open circuit condition has not been corrected. The sensor connection or the sensor itself must be physically inspected and repaired for the error to be resolved permanently.
How much does it cost to repair an E-29 error on an LG microwave?
If only the sensor connector needs to be reseated, there is no parts cost. Replacing a faulty humidity sensor typically costs between $15 and $50 for the part, depending on availability. If the main PCB requires replacement, costs can range from $80 to $200 or more for the component alone, and professional labor will add to the total.

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