LG LMV2031ST Microwave Problems & Error Codes — Overview
The LG LMV2031ST is an over-the-range microwave with inverter technology and sensor cooking features. The most frequent service calls center on sensor-circuit failures that trigger F2, F4, and F17 codes, along with control-board faults that produce E10 and F1 errors. LG publishes a fault-code map for this model that identifies thermistor, humidity-sensor, inverter-communication, and door-latch problems as the primary failure modes. The control board includes a built-in test routine you can trigger by pressing Defrost weight/time for 2 seconds. That test checks the PCB thermistor and PCB humidity sensor for short or open conditions and displays PASS or an error code.
Most Common Problems on This Model
- F2 code and unit stops heating The PCB thermistor has failed open or shorted, putting the temperature reading out of range, so replace the thermistor and check the wiring harness for cuts or corrosion.
- F4 code during sensor cook The PCB humidity sensor circuit is open or shorted, so run the built-in diagnostic test and replace the humidity sensor if it fails.
- E10 code on startup An internal short has been detected in the control board, usually from moisture intrusion or a failed relay, so inspect the board for burnt traces and replace the main control PCB.
- F1 code and all buttons unresponsive The mainboard has failed, often due to a power surge or age-related capacitor failure, so replace the control board.
- F11 or F13 code and no heat Inverter communication has failed or the inverter board is reporting a voltage error, so check the inverter-to-control harness connectors and replace the inverter module if the wiring is intact.
- F17 code and erratic cooking The temperature sensor circuit is reporting out-of-spec values, so measure the thermistor resistance at the PCB connector and replace the sensor if it reads open or far from nominal.
- DOOR code flashing and unit will not start The door latch is not fully engaging or the latch switch has failed, so verify the door closes flush, check for obstructions in the latch path, and replace the door switch if alignment is correct.
- LOC displayed on screen The control lock function is turned on, so press and hold the Stop/Clear button for about three seconds to unlock the panel.
Parts That Commonly Fail
| Part | Notes |
|---|---|
| Main control board (PCB) | Amazon | Fails with E10 or F1 codes, often after moisture exposure or power surges. |
| PCB thermistor | Amazon | Triggers F2 or F17 codes when it shorts or opens; tested by the internal diagnostic. |
| PCB humidity sensor | Amazon | Causes F4 faults; the built-in test checks for short or open conditions. |
| Inverter board | Amazon | Responsible for F11 and F13 inverter-communication and voltage errors. |
Microwave Error Codes for This Model
These codes apply to this model line:
- Lg Microwave Door error code
- Lg Microwave E10 error code
- Lg Microwave F 11 error code
- Lg Microwave F 2 error code
- Lg Microwave F 3 error code
- Lg Microwave F 5 error code
- Lg Microwave F1 error code
- Lg Microwave F11 error code
- Lg Microwave F13 error code
- Lg Microwave F16 error code
- Lg Microwave F17 error code
- Lg Microwave F2 error code
When to Call a Pro
Call a technician if you see E10, F1, F11, F13, or F17 codes after a power reset and basic inspection. These faults require multimeter diagnostics, harness continuity checks, and board-level replacement that involve high-voltage capacitors and inverter circuits. Door-latch and simple sensor faults can often be handled by a confident DIYer with the service manual, but if the built-in test fails or you are uncomfortable working inside a microwave cabinet, get a qualified appliance tech to diagnose and replace the correct module.