LG Microwave F16 Error — What It Means
The F16 error on an LG microwave signals that the unit has detected a heating issue, specifically in the inverter or its cooling system. LG’s fault-code chart identifies F16 as an inverter heat sink error, meaning the inverter circuit that powers the magnetron has either overheated or lost proper cooling.
When F16 appears, the microwave will stop operation to protect the inverter from damage. LG’s official guidance is that this code requires professional service rather than user-level repair. The problem usually lies in the inverter module itself, the cooling fan that keeps the inverter heat sink cool, the temperature sensor circuit, or the wiring connecting these components.
Common Causes
- Failed inverter board The inverter module that powers the magnetron has failed internally or is overheating due to component breakdown.
- Cooling fan motor failure The fan that cools the inverter heat sink has stopped or slowed, allowing the inverter to overheat and trigger the sensor.
- Blocked airflow path Dust, grease, or foreign material has blocked the vents or cooling path around the inverter, preventing adequate airflow.
- Loose or damaged wiring Connectors or wiring between the inverter, fan motor, and control board are loose, corroded, or broken.
- Inverter temperature sensor fault The heat-sink temperature sensing circuit or sensor has failed and is sending a false overheat signal to the control board.
- Door latch interference Packing material or a misaligned door prevents proper closure, which can confuse the control logic and trigger a fault code.
Step-by-Step Fix
- Unplug the microwave for at least 60 seconds to reset the control board, then restore power and test to see if the F16 code returns.
- Check the door for any packing material, racks left inside, or objects blocking the latch, and remove any obstructions so the door closes firmly.
- Inspect the rear and side vents for dust, grease buildup, or blockages, and clean them with a soft brush or vacuum to restore airflow around the inverter.
- Verify the cooling fan runs when the microwave is powered on by listening at the vents or removing the outer cover to observe the fan motor directly.
- Examine inverter wiring and connectors for burn marks, loose plugs, or corroded terminals, and reseat or replace any damaged harness connections.
- Test the inverter board by isolating it from the magnetron and checking for visible burn marks, bulging capacitors, or scorched components on the board surface.
- Replace the failed component (inverter module, fan motor, or sensor assembly) if the fault persists after reset and visual inspection, or call a qualified technician if you cannot identify the failure point.
Parts Often Needed
| Part | Notes |
|---|---|
| Inverter board | Amazon | Match the board number on your existing inverter module label to make sure correct voltage and wattage rating for your model. |
| Cooling fan motor assembly | Amazon | Order the fan motor by your microwave’s full model number to get the correct mounting bracket and connector style. |
| Wiring harness for inverter | Amazon | Use only OEM LG harness if connectors are melted or damaged to maintain proper gauge and heat tolerance. |
When to Call a Pro
LG states that the F16 error requires professional service. If a power reset and visual inspection do not clear the fault, or if you are uncomfortable working around high-voltage components inside the microwave, stop and call a qualified appliance technician. The inverter section retains dangerous voltage even when unplugged, and incorrect repair can damage the magnetron or control board. A technician has the tools to safely discharge capacitors, test inverter output, and replace boards under warranty if applicable.